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Search: id:A081490
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| 1, 2, 4, 9, 19, 36, 62, 99, 149, 214, 296, 397, 519, 664, 834, 1031, 1257, 1514, 1804, 2129, 2491, 2892, 3334, 3819, 4349, 4926, 5552, 6229, 6959, 7744, 8586, 9487, 10449, 11474, 12564, 13721, 14947, 16244, 17614, 19059, 20581, 22182, 23864, 25629
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OFFSET
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1,2
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COMMENT
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First differences are given by A002522 = n^2 + 1. Second differences are odd numbers given by A005408.
a(1)=1, a(2)=2, (a(n+1)-a(n))-(a(n)-a(n-1))=2(n-1)-1 [From Ben Thurston (benpaulthurston(AT)gmail.com), Aug 22 2009]
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FORMULA
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a(1) = 1, a(n) = A081489(n-1) + 1.
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MAPLE
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with (combinat):a:=n->sum(fibonacci(3, i), i=0..n):seq(a(n)+1, n=-1..42); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 25 2008
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MATHEMATICA
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q=2; s=0; lst={1}; Do[s+=n^2; AppendTo[lst, s+n+q], {n, 0, 5!, 1}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), May 25 2009]
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CROSSREFS
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Cf. A002522, A005408, A081489, A081491, A081492.
Sequence in context: A026765 A032175 A000678 this_sequence A129784 A125050 A056186
Adjacent sequences: A081487 A081488 A081489 this_sequence A081491 A081492 A081493
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 25 2003
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EXTENSIONS
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More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 29 2003
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