OFFSET
0,7
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,1,1,0,-1,1,0,-1,-1,0,1).
FORMULA
a(6n) = a(6n+2) = a(6n+3) = a(6n+4) = a(6n+5) = n*(n+1)/2. a(6n+1) = (n-1)*n/2. - Franklin T. Adams-Watters, Oct 27 2014
PROG
(PARI) a(n)=(n^2+(4*((n+2)%3)+7+3*(-1)^n)*n+57+33*(-1)^n/2)\72 \\ Tani Akinari, Oct 27 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved