19670

Appears in sequences

• Weird numbers: abundant (A005101) but not pseudoperfect (A005835).at n=34A006037
• a(n) = [ (3rd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ], where S(n) = {first n+2 positive integers congruent to 2 mod 3}.at n=13A024399
• Truncated square pyramid numbers: a(n) = Sum_{k = n..2*n} k^2.at n=20A050409
• The n-th n-gonal number: a(n) = n*(n^2 - 3*n + 4)/2.at n=35A060354
• a(n) = (2*n - 1)*(11*n^2 - 11*n + 6)/6.at n=17A063492
• Unitary weird numbers: unitary abundant (A034683) but not unitary pseudoperfect (A293188).at n=31A064114
• a(n) = (3+n)*(2 + 33*n + n^2)/6.at n=39A101860
• Triangle read by rows: T(n,k) is the number of permutations of an n-set having k cycles of size > 1 (0<=k<=floor(n/2)).at n=22A136394
• Number of ways to place zero or more nonadjacent 0,0 1,0 2,0 3,1 4,1 5,2 6,3 polyhexes in any orientation on a planar nXnXn triangular grid.at n=7A155335
• a(n) = 16*n^2 + 2*n.at n=34A158056
• Numbers of the form prime(n)*(prime(n)-1)/4.at n=27A171555
• Number of nXnXn 0..6 triangular arrays with each element x equal to the number its neighbors equal to 2,4,1,0,1,0,0 for x=0,1,2,3,4,5,6.at n=5A197751
• Antidiagonal sums of the convolution array A213833.at n=13A213834
• Number of (n+3)X(n+3) 0..1 matrices with each 4X4 subblock idempotent.at n=11A224560
• a(n) = Sum_{i=0..n} digsum_4(i)^4, where digsum_4(i) = A053737(i).at n=43A231667
• 35-gonal numbers: a(n) = n*(33*n-31)/2.at n=35A282851
• Number of permutations of [n] having exactly two nontrivial cycles.at n=4A289950
• Bi-unitary weird numbers: bi-unitary abundant numbers (A292982) that are not bi-unitary pseudoperfect (A292985).at n=36A292986
• Infinitary weird numbers: infinitary abundant numbers (A129656) that are not infinitary pseudoperfect numbers (A306983).at n=37A306984
• On a spirally numbered square grid, with labels starting at 1, this is the number of the last cell that an (n,n+1) leaper reaches before getting trapped, or -1 if it never gets trapped.at n=33A343179