27580

Appears in sequences

• Number of discordant permutations.at n=17A000561
• Numbers k such that phi(sigma(k)+k) = sigma(k-phi(k)), where phi is A000010 and sigma is A000203.at n=36A063710
• a(n) = 280*binomial(n+4,9) + 280*binomial(n+4,8) + 105*binomial(n+3,7) + 77*binomial(n+3,6) + 43*binomial(n+2,5) - 16*binomial(n+2,4) + 20*binomial(n+1,3) - floor(n*(n^2 - 1)*(n^2 - 4)*(n-3)/360).at n=6A064204
• Pell companion numbers A001333 without last digit.at n=11A131607
• 7 times heptagonal numbers: a(n) = 7*n*(5*n-3)/2.at n=40A152777
• Number of 5-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and first differences in -n..n.at n=18A209033
• Number of partitions p of n such that the number of numbers having multiplicity 1 in p is a part and the number of numbers having multiplicity > 1 is not a part.at n=48A241416
• Number of nX3 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=7A281075
• T(n,k) = Number of n X k 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=47A281080
• T(n,k) = Number of n X k 0..1 arrays with no element equal to more than two of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.at n=52A281080
• Squared end-to-end distance of irreducible endless self-avoiding walks of length n for the square lattice.at n=6A334323
• Number of ways to split an integer partition of n into contiguous subsequences with strictly increasing sums.at n=31A336134