19875

Appears in sequences

• Geometric mean of phi(n) and sigma(n) is an integer, n odd.at n=34A015705
• Number of partitions of n into parts not of the form 23k, 23k+9 or 23k-9. Also number of partitions with at most 8 parts of size 1 and differences between parts at distance 10 are greater than 1.at n=37A035997
• Denominators of continued fraction convergents to sqrt(718).at n=10A042383
• Concatenation of the 5 prime factors of composite a(n) is a palindrome.at n=4A046454
• Numbers k such that n | sigma_10(k) + phi(k)^10.at n=13A055704
• Triangle read by rows: colored polyominoes. For n >= 1, 1 <= k <= n, T(n, k) is the number of k-colored n-celled polyominoes, counted up to rotation, reflection and permutation of the colors. Adjacent cells must be different colors. T(n, k) counts only polyominoes that include all k colors.at n=30A088972
• Integers k such that 5*10^k + 51 is prime.at n=11A110983
• Matrix square of triangle A113340.at n=23A113345
• Column 2 of triangle A113345, also equals column 0 of A113350^5.at n=4A113348
• Floor of sum of the first n^2 square roots.at n=31A138357
• Composites that are the sum of two, three, four and five consecutive composite numbers.at n=23A151745
• G.f.: A(x) = exp( Sum_{n>=1} 3*A038500(n) * x^n/n ), where A038500 is the highest power of 3 dividing n.at n=34A161809
• Number of n X 2 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 3 binary array having a sum of two or less, with rows and columns of the latter in lexicographically nondecreasing order.at n=23A227259
• Expansion of phi(x) * chi(x^2)^4 in powers of x where phi(), chi() are Ramanujan theta functions.at n=48A260514
• Expansion of phi(x^2) * chi(x)^4 in powers of x where phi(), chi() are Ramanujan theta functions.at n=24A260515
• Positions of 3's in A264977; positions of 6's in A277330.at n=38A277713
• Number of integer partitions of n with exactly as many ones as the next greatest multiplicity.at n=51A382303