23653

Appears in sequences

• Pseudoprimes to base 5.at n=33A005936
• Number of monomials in expansion of determinant of an n X n Hankel matrix [ t(i+j) ] in terms of its entries.at n=9A019448
• Strong pseudoprimes to base 25.at n=18A020251
• Strong pseudoprimes to base 61.at n=12A020287
• Base 6 digits are, in order, the first n terms of the periodic sequence with initial period 3,0,1.at n=5A037648
• a(n) = 25*n*(n + 1)/2 + 3.at n=43A061793
• a(n) is the smallest number k such that A073813(k) = prime(n).at n=37A073814
• Terms of A073872 that do not change their position in the rearrangement; i.e., values of A073872(n) which equal n(n+1)/2.at n=16A073873
• a(n) = (9n^4 - 18n^3 + 18n^2 - 9n + 2)/2.at n=8A079903
• Triangular numbers whose sum of aliquot divisors is a prime number.at n=17A083676
• Numerator of (9*(n^4 - 2*n^3 + 2*n^2 - n) + 2)/(2*(2*n-1)).at n=8A096430
• Triangular numbers whose digit reversal is the product of 2 palindromes greater than 1.at n=28A115702
• Hexagonal numbers with prime indices.at n=28A117961
• a(n) is such that the a(n)-th composite number is (n-th prime)^2.at n=37A120389
• Triangular numbers congruent to 1 or 5 mod 6.at n=36A128880
• Triangular numbers T such that T+10 is the next prime after T.at n=5A129540
• Triangular numbers t such that t+10 is a prime.at n=29A129755
• Triangular numbers that are the difference of nonnegative cubes.at n=11A129965
• Triangular numbers n*(n+1)/2 with n and n+1 composite, where number of prime factors in n = number of prime factors in n+1. (Prime factors are counted with multiplicity.)at n=39A144486
• Products of three distinct happy primes A035497.at n=34A154717