OFFSET
0,2
FORMULA
a(n) = 2*A005728(n) if n>=1. - R. J. Mathar, Feb 05 2008
PROG
(PARI) T(n, k) = (n+1)*(k+1) - sum(i=0, n, sum(j=0, k, gcd(i, j)>1)); \\ A049627
a(n) = T(n, n); \\ Michel Marcus, Aug 06 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Sean A. Irvine, Aug 05 2021
STATUS
approved