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Search: id:A140155
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| A140155 |
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a(1)=1, a(n)=a(n-1)+n^3 if n odd, a(n)=a(n-1)+ n^4 if n is even. |
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+0
2
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| 1, 17, 44, 300, 425, 1721, 2064, 6160, 6889, 16889, 18220, 38956, 41153, 79569, 82944, 148480, 153393, 258369, 265228, 425228, 434489, 668745, 680912, 1012688, 1028313, 1485289, 1504972, 2119628, 2144017, 2954017, 2983808, 4032384
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)=a(n-1)+{[1-(-1)^n]/2}*n^3+{[1+(-1)^n]/2}*n^4, with a(1)=1 a(n)= (-1/16)-(1/4)*(-1)^n*n+(1/16)*(-1)^n+(1/4)*(-1)^n*n^3+(5/12)*n^3-(3/8)*(-1)^n*n^2+(1/8)*n^2-(1 /60)*n+(1/10)*n^5+(1/4)*(-1)^n*n^4+(3/8)*n^4, with n>=1 - Paolo P. Lava (ppl(AT)spl.at), Jun 06 2008
G.f.: -x*(x^2+1)*(x^6-16*x^5+21*x^4-160*x^3-21*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
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a = {}; r = 3; 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
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Cf. A000027, A000217, A000330, A000537, A000538, A000539, A136047, A140113.
Sequence in context: A112885 A093191 A033703 this_sequence A032698 A120099 A045570
Adjacent sequences: A140152 A140153 A140154 this_sequence A140156 A140157 A140158
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KEYWORD
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nonn
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AUTHOR
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Jasinski Artur (grafix(AT)csl.pl), May 12 2008
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