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Search: id:A064808
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| A064808 |
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The (n+1)st (n+2)-gonal number. |
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+0
9
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| 1, 3, 9, 22, 45, 81, 133, 204, 297, 415, 561, 738, 949, 1197, 1485, 1816, 2193, 2619, 3097, 3630, 4221, 4873, 5589, 6372, 7225, 8151, 9153, 10234, 11397, 12645, 13981, 15408, 16929, 18547, 20265, 22086, 24013, 26049, 28197, 30460, 32841, 35343
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Sum of n terms of the arithmetic progression with first term 1 and common difference n-1. - Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 04 2005
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FORMULA
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a(n)=(n+1)(n^2+2)/2
a(n)=sum{k=0..n, sum{j=0..n, (k-(k-1)*C(0, j-k)}}; a(n)=A006002(n)-A000096(n-2). - Paul Barry (pbarry(AT)wit.ie), Nov 18 2005
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CROSSREFS
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Main diagonal of A057145.
Sequence in context: A063586 A131477 A002128 this_sequence A001937 A086817 A000715
Adjacent sequences: A064805 A064806 A064807 this_sequence A064809 A064810 A064811
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KEYWORD
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easy,nonn
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AUTHOR
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Floor van Lamoen (fvlamoen(AT)hotmail.com), Oct 22 2001
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