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Search: id:A051846
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| A051846 |
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Digits 1..n in strict descending order n..1 interpreted in base n+1. |
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+0
4
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| 1, 7, 57, 586, 7465, 114381, 2054353, 42374116, 987654321, 25678050355, 736867805641, 23136292864686, 789018236134297, 29043982525261081, 1147797409030816545, 48471109094902544776, 2178347851919531492065
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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All odd-indexed (2n+1) terms are divisible by (2n+1). See A051847.
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FORMULA
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a(n) = sum(i*((n+1)^(i-1)), i=1..n)
a(n)=A062806(n+1)/(n+1)-(n+1)^(n+1); a(n)=((n+1)^(n+1)*(n-1) + 1)/n^2 - Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 28 2002
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EXAMPLE
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a(1) = 1, a(2) = 2*3 + 1 = 7, a(3) = 3*(4^2) + 2*4 + 1 = 57, a(4) = 4*(5^3) + 3*(5^2) + 2*5 + 1 = 586
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MAPLE
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a(n) := proc(n) local i; add(i*((n+1)^(i-1)), i=1..n); end;
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PROGRAM
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(PARI) a(n)=((n+1)^(n+1)*(n-1) + 1)/n^2
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CROSSREFS
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The right edge of A051845. Cf. also A023811.
Sequence in context: A082413 A062192 A122649 this_sequence A051816 A015566 A006193
Adjacent sequences: A051843 A051844 A051845 this_sequence A051847 A051848 A051849
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KEYWORD
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easy,nonn
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AUTHOR
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Antti Karttunen Dec 13 1999
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