21508

Appears in sequences

• a(n) = T(n, 2*n-5), T given by A027926.at n=18A027928
• Number of partitions of n into parts not of the form 15k, 15k+6 or 15k-6. Also number of partitions with at most 5 parts of size 1 and differences between parts at distance 6 are greater than 1.at n=40A035960
• a(n) = T(n,n-5), array T as in A055801.at n=38A055805
• a(n) = A000695(A014486(n)).at n=19A083931
• Numbers n such that if p=prime(n), then p, p+6, p+12, p+18 are consecutive primes with p=6*k+5 for some k, where prime(n) denotes n-th prime.at n=34A090835
• Least number 2k such that p^2 divides the numerator of the Bernoulli number B(2k), where p is the n-th irregular prime, A000928(n).at n=15A092681
• Numbers n, not divisible by 3, 5, 7 or 11, such that A000203(n)-n-1 and 2*n+1-A000203(n) are prime numbers.at n=10A180268
• Number of ways to place 2n nonattacking kings on a vertical cylinder 4 X 2n.at n=8A195590
• Number of ways to place 9n nonattacking kings on an 18 X 2n cylindrical chessboard.at n=1A195653
• Number of partitions of n containing m(1) as a part, where m denotes multiplicity.at n=42A240486
• Number of partitions of n the largest part of which, call it m, appears once, m-1 appears at most twice, m-2 appears at most thrice, etc.at n=39A244393
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 539", based on the 5-celled von Neumann neighborhood.at n=27A272803
• Numbers that are the sum of eight fourth powers in nine or more ways.at n=25A345584
• Numbers that are the sum of eight fourth powers in ten or more ways.at n=12A345585
• Numbers that are the sum of eight fourth powers in exactly ten ways.at n=9A345842
• Largest even k such that h(-k) = 2n, where h(D) is the class number of the quadratic field with discriminant D; or 0 if no such k exists.at n=9A357573