OFFSET
0,4
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,4,-4,-6,6,4,-4,-1,1).
FORMULA
a(n) = n^3/8 +n^2/16 -15/32 +n^4/16 +(-1)^n*( n^3/8+3*n^2/16-n-17/32 ).
G.f.: ( 1-2*x-4*x^2+2*x^3-18*x^4+2*x^5-4*x^6-2*x^7+x^8 ) / ( (1+x)^4*(-1+x)^5 ).
a(n)= +a(n-1) +4*a(n-2) -4*a(n-3) -6*a(n-4) +6*a(n-5) +4*a(n-6) -4*a(n-7) -a(n-8) +a(n-9).
PROG
(PARI) A171733(n)=if( bittest(n, 0), n, -1-n) +(n\=2)^2 +2*n^3 +n^4
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Paul Curtz, Dec 17 2009
STATUS
approved