A140143 - OEIS

A140143

a(1)=1, a(n)=a(n-1)+n^0 if n odd, a(n)=a(n-1)+ n^5 if n is even.

1, 33, 34, 1058, 1059, 8835, 8836, 41604, 41605, 141605, 141606, 390438, 390439, 928263, 928264, 1976840, 1976841, 3866409, 3866410, 7066410, 7066411, 12220043, 12220044, 20182668, 20182669, 32064045, 32064046

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..27.

FORMULA

a(n)=a(n-1)+6a(n-2)-6a(n-3)-15a(n-4)+15a(n-5)+20a(n-6)-20a(n-7)-15a(n-8)+15a(n-9)+6a(n-10)-6a(n-11)-a(n-12)+a(n-13). G.f.: x*(-1-32*x+5*x^2-832*x^3-10*x^4-2112*x^5+10*x^6-832*x^7-5*x^8-32*x^9+x^10 )/((1+x)^6*(x-1)^7). [From R. J. Mathar, Feb 22 2009]

MATHEMATICA

a = {}; r = 0; s = 5; 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*)

CROSSREFS

Cf. A000027, A000217, A000330, A000537, A000538, A000539, A136047, A140113.

Sequence in context: A260678 A329658 A344139 * A041543 A144425 A180329

Adjacent sequences: A140140 A140141 A140142 * A140144 A140145 A140146

KEYWORD

nonn

AUTHOR

Artur Jasinski, May 12 2008, corrected May 17 2008

STATUS

approved