Patterns /Number Theory
Semiprime Numbers
A semiprime is a product of exactly two primes, counted with multiplicity — 15 = 3 × 5, and 49 = 7 × 7 counts too.
How long might semiprime numbers take?
1 in 4.8 per roll · 5 rolls on average.
At one daily specimen a day, the mean is about 0 years. A 50% chance takes 3 rolls; 90% takes 10.
7 daily rolls
80.80%
30 daily rolls
99.92%
365 daily rolls
100.00%
99.92% chance of at least one match in 30 independent rolls.
Waiting times are averages, not deadlines. Previous misses do not increase the next roll’s chance. Only Daily Specimens stamp your Atlas.
Semiprimes are the next step out from primes, and there are more of them across this range than there are primes. Their count is shown above, computed by full factorisation of every number.
They matter well beyond number games: the difficulty of splitting a large semiprime back into its two factors is the assumption RSA encryption rests on. At six digits that is trivial, but the structure is the same.
On RNGdle, semiprimality sits in the factorization group alongside squares, cubes and divisor counts, and the group's decay weighting keeps a number from stacking several overlapping factorisation claims at full value.
Highest-scoring examples
The best-scoring numbers of four digits or more that carry this pattern. Shorter numbers are excluded here because their length alone dominates any score ranking.
Smallest examples
The first numbers in the range that match this pattern.
Related number theory patterns
Prime Numbers
A prime has no divisors other than 1 and itself. They are the building blocks every other number is assembled from.
Perfect Squares
A perfect square is some whole number times itself: 144 = 12², 10000 = 100². The range ends neatly on 1,000,000 = 1000².
Perfect Cubes
A perfect cube is a whole number raised to the third power: 216 = 6³, 970299 = 99³. There are only about a hundred in the entire range.
Powers of Two
Each power of two is double the last: 1, 2, 4, 8, 16, and on up through 1024, 65536 and 524288. Doubling exhausts the range in only twenty steps.
Fibonacci Numbers
Each Fibonacci number is the sum of the two before it: 1, 1, 2, 3, 5, 8, 13 … reaching 832040 before the range runs out.