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A100674 a(1) = 1; a(n+1) = Sum_{k=1..n} a(gcd(k, a(n))). 1
1, 1, 2, 3, 5, 9, 8, 9, 10, 13, 10, 27, 24, 59, 14, 80, 127, 17, 144, 169, 43, 21, 84, 183, 32, 126, 184, 140, 441, 124, 44, 74, 32, 209, 204, 463, 36, 617, 38, 798, 1025, 1124, 62, 86, 105, 422, 46, 551, 774, 222, 157, 51, 476, 820, 1492, 81, 470, 186, 183, 78, 459, 884 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

MAPLE

a[1]:=1: for n from 2 to 70 do b[n]:=[seq(a[gcd(k, a[n-1])], k=1..n-1)]: a[n]:=sum(b[n][j], j=1..nops(b[n])) od: seq(a[n], n=1..70);

MATHEMATICA

a[1] = 1; a[n_] := a[n] = Plus @@ a /@ GCD[Range[n - 1], a[n - 1]]; Table[ a[n], {n, 62}] (* Robert G. Wilson v, Dec 09 2004 *)

PROG

(GAP) a:=[1];; for n in [2..65] do a[n]:=Sum([1..n-1], k->a[Gcd(k, a[n-1])]); od; a; # Muniru A Asiru, Oct 21 2018

CROSSREFS

Sequence in context: A323390 A324886 A277332 * A058314 A072735 A127149

Adjacent sequences:  A100671 A100672 A100673 * A100675 A100676 A100677

KEYWORD

nonn

AUTHOR

Leroy Quet, Dec 06 2004

EXTENSIONS

More terms from Emeric Deutsch and Robert G. Wilson v, Dec 09 2004

STATUS

approved

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Last modified November 21 09:14 EST 2019. Contains 329362 sequences. (Running on oeis4.)