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Search: id:A081219
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| A081219 |
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One sixtieth the product of primitive Pythagorean triangles' sides whose odd values differ by 2. |
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+0
1
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| 1, 34, 259, 1092, 3333, 8294, 17927, 34952, 62985, 106666, 171787, 265420, 396045, 573678, 809999, 1118480, 1514513, 2015538, 2641171, 3413332, 4356373, 5497206, 6865431, 8493464, 10416665, 12673466, 15305499, 18357724, 21878557, 25919998
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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If Y and Z are 2-blocks of a (2n+1)-set X then a(n-2) is the number of 7-subsets of X intersecting both Y and Z. - Milan R. Janjic (agnus(AT)blic.net), Oct 28 2007
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LINKS
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Milan Janjic, Two Enumerative Functions
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FORMULA
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a(n)=n*(16*n^4 - 1)/15.
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CROSSREFS
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Cf. A081752.
Adjacent sequences: A081216 A081217 A081218 this_sequence A081220 A081221 A081222
Sequence in context: A020869 A055716 A020872 this_sequence A027006 A101092 A034978
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KEYWORD
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easy,nonn
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AUTHOR
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Lekraj Beedassy (blekraj(AT)yahoo.com), Apr 18 2003
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EXTENSIONS
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More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 28 2003
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