25201

Appears in sequences

• Strong pseudoprimes to base 23.at n=17A020249
• Number of singular 2 X 2 matrices over Z(n) (i.e., with determinant = 0).at n=28A020478
• Number of noninvertible 2 X 2 matrices over Z/nZ (determinant is a divisor of 0).at n=27A020479
• Numbers k such that k^2 and k^3 have the same set of digits.at n=33A029797
• Base 5 digits are, in order, the first n terms of the periodic sequence with initial period 1,3,0.at n=6A037598
• a(n) is the least multiple of n such that a(n) = 1 mod k for all integers k with 1 < k < n and k relatively prime to n.at n=10A055006
• Composite numbers m such that phi(m)*sigma(m) is divisible by m-1.at n=30A065149
• Diagonal in array of n-gonal numbers A081422.at n=28A081437
• Number of pairs with two different elements which can be obtained by selecting unique elements from two sets with n+1 and n^2 elements respectively and n common elements.at n=29A085490
• a(n) is smallest positive integer multiple of n-th prime, say k*prime(n), such that k*prime(n) == 1 (mod j) for each integer j with 1 < j < prime(n).at n=4A094998
• Row sums of A095167.at n=28A095170
• Number of Pythagorean quadruples mod n; i.e., number of solutions to w^2 + x^2 + y^2 = z^2 mod n.at n=28A096018
• G.f.: (x-1)/(-2*x^2 + 3*x^3 + 2*x - 1).at n=19A102785
• Triangle, read by rows, T(n, k) = T(n, k-1) + (k+1)*n!, T(n, 0) = 1.at n=30A105064
• Highly composite numbers + 1.at n=23A135372
• a(n) = 900*n + 1.at n=27A158407
• a(n) = 28*n^2 + 1.at n=30A158556
• a(n) = 5*n! + 1.at n=7A173319
• Triangle T(n, k) = n! * binomial(n, k)^2 - n! + 1, read by rows.at n=22A174689
• Triangle T(n, k) = n! * binomial(n, k)^2 - n! + 1, read by rows.at n=26A174689