A065504 a(n+1) = a(n) + n + the number of a(k)'s <= n, 1 <= k <= n and a(1) = 1.

1, 3, 6, 11, 17, 24, 33, 43, 54, 66, 79, 94, 110, 127, 145, 164, 184, 206, 229, 253, 278, 304, 331, 359, 389, 420, 452, 485, 519, 554, 590, 627, 665, 705, 746, 788, 831, 875, 920, 966, 1013, 1061, 1110, 1161, 1213, 1266, 1320, 1375, 1431, 1488, 1546, 1605

Offset

1,2

Links

Table of n, a(n) for n=1..52.

Example

a(7) = a(6) + 6 + the number of a(k)'s <= 6 = 24 + 6 + 3 ( a(3) is <= 6) = 33.

Mathematica

f[1] = 1; f[n_] := f[n] = Block[ {k = 1}, While[ f[k] < n, k++ ]; k--; Return[ f[n - 1] + (n - 1) + k]]; Table[ f[n], {n, 1, 60} ]

Crossrefs

Sequence in context: A194142 A174648 A178419 * A071619 A025735 A023601

Adjacent sequences: A065501 A065502 A065503 * A065505 A065506 A065507

Keyword

nonn

Author

Robert G. Wilson v, Nov 25 2001

Status

approved