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A123886
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a(0)=1. a(n) = a(n-1) + (number of earlier terms {ie, terms a(0) through a(n-1)} which divide n).
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2
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1, 2, 4, 5, 8, 10, 12, 13, 17, 18, 22, 23, 27, 29, 31, 33, 37, 39, 42, 43, 48, 49, 52, 54, 59, 61, 64, 66, 69, 71, 75, 77, 81, 83, 86, 88, 93, 95, 97, 100, 106, 107, 110, 112, 116, 118, 121, 122, 128, 130, 134, 136, 141, 142, 147, 149, 153, 154, 157, 159, 165, 167, 170
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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EXAMPLE
| Among terms a(0) through a(5) there are two terms which divide 6, a(0)=1, a(1)=2. So a(6) = a(5) + 2 = 12.
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MAPLE
| A123886 := proc(maxn) local a, nexta, n, i ; a := [1] ; for n from 2 to maxn do nexta := op(n-1, a) ; for i from 1 to n-1 do if (n-1) mod op(i, a) = 0 then nexta := nexta +1 ; fi ; od ; a := [op(a), nexta] ; od ; RETURN(a) ; end: maxn := 100 : alist := A123886(maxn) : for i from 1 to maxn do printf("%d, ", op(i, alist)) ; end : - R. J. Mathar (mathar(AT)strw.leidenuniv.n), Oct 21 2006
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MATHEMATICA
| f[l_List] := Append[l, Last[l] + Length[Select[l, Mod[Length[l], # ] == 0 &]]]; Nest[f, {1}, 63] (*Chandler*)
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CROSSREFS
| Cf. A123885.
Sequence in context: A112777 A188972 A047612 * A005242 A188975 A115392
Adjacent sequences: A123883 A123884 A123885 * A123887 A123888 A123889
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KEYWORD
| easy,nonn
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AUTHOR
| Leroy Quet Oct 17 2006
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 19 2006
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 21 2006
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