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Search: id:A071355
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| 3, 12, 25, 42, 63, 88, 117, 150, 187, 228, 273, 322, 375, 432, 493, 558, 627, 700, 777, 858, 943, 1032, 1125, 1222, 1323, 1428, 1537, 1650, 1767, 1888, 2013, 2142, 2275, 2412, 2553, 2698, 2847, 3000, 3157, 3318, 3483, 3652, 3825, 4002, 4183, 4368, 4557, 4750, 4947
(list; graph; listen)
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OFFSET
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-1,1
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COMMENT
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If Y is a 3-subset of an 2n-set X then, for n>=3, a(n-3) is the number of (2 n-2)-subsets of X having at least two elements in common with Y. - Milan R. Janjic (agnus(AT)blic.net), Dec 16 2007
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FORMULA
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a(n) = (n+4)*(2*n+3). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 18 2004
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MATHEMATICA
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lst={}; Do[AppendTo[lst, 2*n^2+11*n+12], {n, -2, 5!}]; lst...and/or... s=-3; lst={}; Do[s+=n+1; AppendTo[lst, s], {n, 0, 6!, 4}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 25 2008]
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CROSSREFS
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a(n)=A100345(n+4, n-1) for n>0.
Sequence in context: A076506 A009776 A068967 this_sequence A110859 A125614 A061936
Adjacent sequences: A071352 A071353 A071354 this_sequence A071356 A071357 A071358
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jun 12 2002
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