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A033455
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Convolution of nonzero squares A000290 with themselves.
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3
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1, 8, 34, 104, 259, 560, 1092, 1968, 3333, 5368, 8294, 12376, 17927, 25312, 34952, 47328, 62985, 82536, 106666, 136136, 171787, 214544, 265420, 325520, 396045, 478296, 573678, 683704, 809999, 954304
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Total area of all square regions from an n X n grid. e.g. n=3, there are 9 individual squares, 4 2 X 2's and 1 3 X 3, total area 9+16+9=34, hence a(3)=34 - Jon Perry (perry(AT)globalnet.co.uk), Jul 29 2003
If X is an n-set and Y and Z disjoint 2-subsets of X then a(n) is equal to the number of 7-subests of X intersecting both Y and Z. - Milan R. Janjic (agnus(AT)blic.net), Aug 26 2007
Every fourth term is odd. However, there are no primes in the sequence. - Zak Seidov Feb 28 2011
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LINKS
| Milan Janjic, Two Enumerative Functions
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FORMULA
| a(n+2) = (n^5-n)/30 = A061167(n)/30. - Henry Bottomley (se16(AT)btinternet.com), Apr 18 2001
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MATHEMATICA
| Table[(n^5-n)/30, {n, 2, 60}] (*From Vladimir Joseph Stephan Orlovsky, Feb 28 2011*)
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CROSSREFS
| Cf. A001249.
Sequence in context: A024847 A154516 A066804 * A172202 A053298 A196311
Adjacent sequences: A033452 A033453 A033454 * A033456 A033457 A033458
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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