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Search: id:A145608
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| A145608 |
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Numbers a(n)=k such that (1/3)*(5*(2k+1)^2-2) is A057080(n)^2 |
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+0
1
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| 0, 3, 27, 216, 1704, 13419, 105651, 831792, 6548688, 51557715, 405913035, 3195746568, 25160059512, 198084729531, 1559517776739, 12278057484384, 96664942098336, 761041479302307, 5991666892320123, 47172293659258680, 371386682381749320, 2923921165394735883, 23019982640776137747
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OFFSET
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0,2
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FORMULA
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a(n+2)=8*a(n+1)-a(n)+3
a(n)=(A070997(n)-1)/2 = 3*A076765(n-1). - R. J. Mathar, Oct 16 2008
a(n)=-(1/2)+(1/4)*{[4-sqrt(15)]^n+[4+sqrt(15)]^n}-(1/20)*sqrt(15)*{[4-sqrt(15)]^n-[4+sqrt(15)]^n}, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Nov 25 2008]
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CROSSREFS
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Cf. A057080, A131571, A145607.
Sequence in context: A118996 A043023 A087426 this_sequence A083713 A065100 A035088
Adjacent sequences: A145605 A145606 A145607 this_sequence A145609 A145610 A145611
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KEYWORD
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easy,nonn
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AUTHOR
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Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 14 2008
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EXTENSIONS
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Made definition and sequence consistent. Changed offset to 0. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 16 2008
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