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A145607
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Numbers a(n)=k such that (3*(2k+1)^2+2)/5 is A070997(n)^2
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1
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0, 4, 35, 279, 2200, 17324, 136395, 1073839, 8454320, 66560724, 524031475, 4125691079, 32481497160, 255726286204, 2013328792475, 15850904053599, 124793903636320, 982500325036964, 7735208696659395, 60899169248238199
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n+2)=8*a(n+1)-a(n)+3.
G.f.: x(4-x)/((1-x)(1-8x+x^2)). a(n)=(A057080(n)-1)/2. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 24 2008
a(n)=-(1/2)+(1/4)*{[4-sqrt(15)]^n+[4+sqrt(15)]^n}-(1/12)*sqrt(15)*{[4-sqrt(15)]^n- [4+sqrt(15)]^n}, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 25 2008]
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CROSSREFS
| Cf. A070997, A131751, first differences: A001091
Sequence in context: A128811 A104526 A174436 * A188527 A026304 A104456
Adjacent sequences: A145604 A145605 A145606 * A145608 A145609 A145610
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KEYWORD
| easy,nonn
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AUTHOR
| Richard Choulet (richardchoulet(AT)yahoo.fr), Oct 14 2008
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EXTENSIONS
| a(4) corrected, extended, definition corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 24 2008
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