19320

Appears in sequences

• Number of trees with n unlabeled nodes.at n=16A000055
• Terms in certain determinants.at n=5A002776
• Number of connected trivalent (or cubic) labeled graphs with 2n nodes.at n=4A004109
• Number of labeled trivalent (or cubic) 2-connected graphs with 2n nodes.at n=3A007099
• [ n(n-1)(n-2)(n-3)/11 ].at n=23A011921
• Perimeters of more than one primitive Pythagorean triangle.at n=35A024408
• a(n) = (d(n)-r(n))/2, where d = A026049 and r is the periodic sequence with fundamental period (1,0,0,1).at n=44A026050
• dot product (n,n-1,...2,1).(3,4,...,n,1,2).at n=43A026054
• a(n) = n*(n + ceiling(2^n/12)).at n=14A029929
• Number of reversible strings with n-1 beads of 2 colors. 6 beads are black. Strings are not palindromic.at n=13A032093
• "DHK[ 5 ]" (bracelet, identity, unlabeled, 5 parts) transform of 1,1,1,1,...at n=41A032246
• Triangle of numbers a(n,k) = number of terms in n X n determinant with 2 adjacent diagonals of k and k-1 0's (0<=k<=n).at n=39A047922
• Smallest positive number of "triangular" shuffles of n(n+1)/2 cards needed to restore them to their original order.at n=17A048782
• Number of 4-block ordered tricoverings of an unlabeled n-set.at n=44A060488
• Write 1, 2, 3, 4, ... counterclockwise in a hexagonal spiral around 0 starting left down, then a(n) is the sequence found by reading from 0 in the vertical upward direction.at n=40A063436
• a(0)=1, a(n) = 8*n*(2*n-1).at n=35A067239
• Numbers k such that the sign of core(k)-phi(k) is not equal to 2*mu(k)^2-1, where core(k) is the squarefree part of k.at n=34A070237
• Numbers k such that d(phi(k)) = phi(d(k)), where d=A000005 and phi=A000010.at n=32A078148
• Numbers n with property that n sets a new record for number of ways to write n as the sum of a brilliant number and a prime.at n=44A084418
• a(n) = (prime(n)-1)*(prime(n)+1).at n=33A084920