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Search: id:A130708
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| A130708 |
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Number of compositions of n such that every part divides the largest part. |
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+0
1
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| 1, 1, 2, 4, 8, 14, 26, 45, 79, 137, 241, 423, 754, 1343, 2410, 4344, 7870, 14305, 26103, 47763, 87649, 161229, 297251, 549108, 1016243, 1883898, 3497761, 6503420, 12107958, 22570221, 42121298, 78692765, 147165225, 275476533, 516115940
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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G.f.: 1 + Sum_{n>0} x^n/((1-Sum_{d divides n} x^d)*(1-Sum_{d divides n,d<n} x^d)).
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MAPLE
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A130708 := proc(n) local gf, den1, den2, i, d ; gf := 1 ; for i from 1 to n do den1 := 1 ; den2 := 1 ; for d in numtheory[divisors](i) do den1 := den1-x^d ; if d < i then den2 := den2-x^d ; fi ; od ; gf := taylor(gf+x^i/den1/den2, x=0, n+1) ; od: coeftayl(gf, x=0, n) ; end: seq(A130708(n), n=0..40) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 28 2007
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CROSSREFS
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Cf. A100346, A018818, A083710, A097986, A117086.
Sequence in context: A036609 A027557 A120545 this_sequence A054193 A117633 A135491
Adjacent sequences: A130705 A130706 A130707 this_sequence A130709 A130710 A130711
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 01 2007
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 28 2007
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