28497

Appears in sequences

• Pentagonal numbers (A000326) which are the sum of 2 other positive pentagonal numbers.at n=33A136117
• a(n) = sum of all divisors of all numbers k such that n^2 <= k < (n+1)^2.at n=19A168012
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 577", based on the 5-celled von Neumann neighborhood.at n=31A273024
• a(n) = (A001359(n+1)^2 - 1)/24, where A001359 = lesser of twin primes; or: pentagonal numbers (A000326) whose indices are twin ranks (A002822).at n=31A308344
• Number of integer partitions of n whose first differences (assuming the last part is zero) are not unimodal.at n=39A332284
• Number of quadrilateral regions in an equilateral triangular "frame" of size n (see Comments in A328526 for definition).at n=17A333033
• Numbers which are the product of two S-primes (A057948) in exactly three ways.at n=27A343828
• Number of integer partitions of n with at least one part of odd multiplicity that is not the first or last.at n=39A349061
• Pentagonal numbers which are products of four distinct primes.at n=22A381919
• Triangular array read by rows: T(n,k) is the number of n-node Stanley graphs containing exactly k connected components, n>=0, 0<=k<=n.at n=50A383656
• Triangle read by rows: T(n,k) = number of connected quartic graphs on n vertices with crossing number k for n >= 1, k >= 0.at n=62A390644