A105434 a(1)=1. a(n+1) = a(n) + (number of terms, from among the first n terms of the sequence, which occur among (d(a(1)),d(a(2)),d(a(3)),...d(a(n))), where d(n) = A000005(n)).

1, 2, 4, 6, 9, 12, 16, 20, 24, 28, 32, 36, 41, 46, 51, 56, 61, 66, 71, 76, 81, 86, 91, 96, 102, 108, 114, 120, 127, 134, 141, 148, 155, 162, 169, 176, 183, 190, 197, 204, 211, 218, 225, 232, 239, 246, 253, 260, 267, 274, 281, 288, 295, 302, 309, 316, 323, 330, 337

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..5000

Mathematica

f[l_] := Append[l, l[[ -1]] + Count[MemberQ[l, # ] & /@ Union@DivisorSigma[0, l], True]]; Nest[f, {1}, 58]

Crossrefs

Cf. A000005. A variant of A130798.

Sequence in context: A155752 A145801 A033291 * A145196 A061536 A095114

Adjacent sequences: A105431 A105432 A105433 * A105435 A105436 A105437

Keyword

nonn

Author

Robert G. Wilson v, Aug 26 2007

Status

approved