

A072493


a(1)=1, a(n) = ceiling((Sum_{k=1..n1} a(k))/3).


82



1, 1, 1, 1, 2, 2, 3, 4, 5, 7, 9, 12, 16, 22, 29, 39, 52, 69, 92, 123, 164, 218, 291, 388, 517, 690, 920, 1226, 1635, 2180, 2907, 3876, 5168, 6890, 9187, 12249, 16332, 21776, 29035, 38713, 51618, 68824, 91765, 122353, 163138, 217517, 290023, 386697
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OFFSET

1,5


COMMENTS

Is this sequence, with its first 8 terms removed, the same as A005427? See also the similar conjecture with A005428/A073941.  Ralf Stephan, Apr 04 2003
Yes; the first 8 terms sum to 15, so upon dividing by 3 they are equivalent to the +5 in the formula for A005427.  Charlie Neder, Jan 10 2019


LINKS

Michel Marcus, Table of n, a(n) for n = 1..1000


FORMULA

a(n) = ceiling(c*(4/3)^n1/2) where c=0.389324199524937508840138455...


MATHEMATICA

f[s_] := Append[s, Ceiling[Plus @@ s/3]]; Nest[f, {1}, 52] (* Robert G. Wilson v, Jul 07 2006 *)


PROG

(PARI) lista(nn) = {va = vector(nn); va[1] = 1; for (n=2, nn, va[n] = ceil(sum(k=1, n1, va[k])/3); ); va; } \\ Michel Marcus, Apr 16 2015


CROSSREFS

Cf. A073941, A005427, A005428.
Sequence in context: A182097 A290697 A290821 * A064324 A173090 A032277
Adjacent sequences: A072490 A072491 A072492 * A072494 A072495 A072496


KEYWORD

nonn


AUTHOR

Benoit Cloitre, Nov 22 2002


STATUS

approved



