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A140146
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a(1)=1, a(n)=a(n-1)+n^1 if n odd, a(n)=a(n-1)+ n^4 if n is even.
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1
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1, 17, 20, 276, 281, 1577, 1584, 5680, 5689, 15689, 15700, 36436, 36449, 74865, 74880, 140416, 140433, 245409, 245428, 405428, 405449, 639705, 639728, 971504, 971529, 1428505, 1428532, 2043188, 2043217, 2853217, 2853248, 3901824, 3901857
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| a(n)=a(n-1)+{[1-(-1)^n]/2}*n+{[1+(-1)^n]/2}*n^4, with a(1)=1 a(n)=(1/8)-(1/2)*(-1)^n*n-(1/8)*(-1)^n+(1/2)*(-1)^n*n^3+(1/6)*n^3+(1/4)*n^2+(7/30)*n+(1/10)*n^5+(1/4)*( -1)^n*n^4+(1/4)*n^4, with n>=1 - Paolo P. Lava (paoloplava(AT)gmail.com), Jun 06 2008
G.f.: -x*(x^2+1)*(x^6-16*x^5-3*x^4-160*x^3+3*x^2-16*x-1)/((1+x)^5*(x-1)^6). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 22 2009]
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MATHEMATICA
| a = {}; r = 1; s = 4; Do[k = 0; Do[k = k + (Sin[Pi m/2]^2) m^r + (Cos[Pi m/2]^2) m^s, {m, 1, n}]; AppendTo[a, k], {n, 1, 100}]; a (*Artur Jasinski*)
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CROSSREFS
| Cf. A000027, A000217, A000330, A000537, A000538, A000539, A136047, A140113.
Sequence in context: A146169 A045020 A069961 * A039502 A039505 A166875
Adjacent sequences: A140143 A140144 A140145 * A140147 A140148 A140149
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KEYWORD
| nonn
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AUTHOR
| Jasinski Artur (grafix(AT)csl.pl), May 12 2008
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