OFFSET
1,1
EXAMPLE
13352 = P(52) + P(79) = P(29) + P(90) = P(17) + P(93) = P(10) + P(94), where P(n) is the n-th pentagonal number A000326.
PROG
(PARI) is(k) = sum(i=1, sqrt(1+12*k)\6, sqrt(1+24*k+12*i-36*i*i)%6==5) == 4; \\ Jinyuan Wang, Mar 06 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Olivier Gérard, Mar 05 2020
STATUS
approved