OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
Michael Boardman, Proof Without Words: Pythagorean Runs, Math. Mag., 73 (2000), 59.
FORMULA
a(n) = n + floor((sqrt(8*n+1)-1)/2)*(3*floor((sqrt(8*n+1)-1)/2)+1)/2. - Robert Israel, Sep 20 2017
MAPLE
seq(seq(2*k^2+k+j, j=0..k), k=0..10); # Robert Israel, Sep 20 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Sep 19 2017
STATUS
approved