A395932 Main diagonal of A396981.

1, 1, 6, 50, 600, 8028, 118124, 2239344, 44339040, 924118272, 20313753096, 544873631616, 14920424467200, 420930757866240, 12283618766690304, 371384787345228000, 13230401127979507200, 476868219163709184000, 17514571789229243904000, 657990721584550597939200, 25335867498073940938060800

Offset

0,3

Links

Table of n, a(n) for n=0..20.

Prog

(PARI) A002024(n) = (sqrtint(8*n-7)+1)\2
a(n) = my(v1 = vector(A002024(n+1), i, 0), v2 = vector(n+1, i, 0), v3); v1[1] = n; v2[1] = 1; for(i=2, #v1, v1[i] = v1[i-1] - A002024(v1[i-1])); v1 = Vecrev(v1); for(i=2, #v1, v3 = vector(n+1, i, 0); v3[1] = 1; A = v1[i] - v1[i-1]; for(j=1, n, v3[j+1] = v2[j+1] + (j+A-1)*v3[j]); v2 = v3); v2[n+1]

Crossrefs

Cf. A002024, A396981.

Sequence in context: A105617 A297926 A386015 * A094072 A361193 A363315

Adjacent sequences: A395929 A395930 A395931 * A395933 A395934 A395935

Keyword

nonn

Author

Mikhail Kurkov, Jun 12 2026

Status

approved