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Search: id:A107461
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| A107461 |
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Number of gap-free compositions of n into distinct parts, cf. A107428. |
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+0
1
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| 1, 1, 3, 1, 3, 7, 3, 1, 9, 25, 3, 7, 3, 25, 129, 1, 3, 31, 3, 121, 729, 25, 3, 7, 123, 25, 729, 5041, 3, 151, 3, 1, 729, 25, 5163, 40327, 3, 25, 729, 121, 3, 5071, 3, 40321, 363729, 25, 3, 7, 5043, 145, 729, 40321, 3, 362911, 3628923, 5041, 729, 25, 3, 40447, 3, 25
(list; graph; listen)
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OFFSET
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1,3
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FORMULA
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G.f.: Sum_{k>0} k!*x^(k*(k+1)/2)/(1-x^k).
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EXAMPLE
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a(6)=7 because we have 6,123,132,213,231,312 and 321.
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MAPLE
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G:=sum(k!*x^(k*(k+1)/2)/(1-x^k), k=1..20): Gser:=series(G, x=0, 73): seq(coeff(Gser, x^n), n=1..70); (Deutsch)
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CROSSREFS
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Sequence in context: A122507 A094250 A114972 this_sequence A035619 A092689 A064434
Adjacent sequences: A107458 A107459 A107460 this_sequence A107462 A107463 A107464
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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), May 26 2005
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 19 2005
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