OFFSET
1,2
COMMENTS
Subsequence of A062861.
Contains A212015 as a subsequence.
A174069 is a subsequence. - Altug Alkan, Dec 24 2015
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
N:= 1000: # to get all terms <=N
g:= x -> x*(x+1)*(2*x+1)/6:
S:= select(`<=`, {seq(seq(g(b)-g(a), a= -b-1 .. b-2), b = 1..floor((sqrt(2*N-1)+1)/2))}, N):
sort(convert(S, list)); # Robert Israel, Jan 05 2016
PROG
(PARI) { isA212016(t) = fordiv(6*t, k, if(k==1, next); z=(k^2-1)/3; if(issquare(4*t/k-z), return(k)); if(z>4*t/k, break); ); 0 }
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Max Alekseyev, Apr 26 2012
STATUS
approved