20538

Appears in sequences

• Number of partitions satisfying cn(2,5) + cn(3,5) <= cn(1,5) + cn(4,5).at n=38A039895
• Write the numbers from 1 to n^2 in a spiraling square; a(n) is the total of the sums of the two diagonals.at n=25A059924
• a(n) is the smallest k such that (k^3 + 1)/(n^3 + 1) is an integer > 1.at n=45A065964
• Numbers which are sums of two, three and four cubes.at n=26A085337
• Numbers which are sums of two, three, four and also sums of five cubes.at n=25A085338
• Numbers k such that (k / sum of digits of k) and (k+1 / sum of digits of k+1) are both semiprime.at n=34A085774
• a(n) = Sum_{k=0..floor(n/7)} C(n-5*k,2*k).at n=32A098574
• Row sums of triangle A113993, where column k equals column 0 of A113983^(k+1).at n=9A113997
• a(n) = a(n-1) - 49*a(n-2), a(0)=1, a(1)=7.at n=5A133669
• Numbers n that raised to the powers from 1 to k (with k>=1) are multiple of the sum of their digits (n raised to k+1 must not be a multiple). Case k=8.at n=36A135193
• Number of n X n arrays of squares of integers with every 2X2 subblock summing to 26.at n=6A159226
• Numbers m such that 2520*m/k + 1 is a prime for k = 1,...,7.at n=2A208549
• Number of length 4 1..(n+2) arrays with no leading or trailing partial sum equal to a prime and no consecutive values equal.at n=19A254221
• Non-unitary amicable numbers.at n=19A259037
• Larger of a non-unitary amicable pair.at n=9A259039
• Twice-partitioned numbers where the first partition is strict and the latter partitions are constant.at n=30A279786
• Nonunitary superperfect numbers: numbers k such that nusigma(nusigma(k)) = k, where nusigma(k) = sigma(k) - usigma(k) is the sum of nonunitary divisors of k (A048146).at n=22A329884
• Expansion of 1/(1 - x^2 - x^7).at n=64A369813
• Numbers k such that k and k+1 are both terms in A377732.at n=23A377733
• a(n) = Sum_{k=0..floor(2*n/7)} binomial(2*n-5*k,2*k).at n=16A392398