A333007 Perfect squares that are sum of two nonzero pentagonal numbers.

36, 121, 196, 400, 625, 1225, 1521, 3481, 5776, 7056, 7225, 8464, 8836, 9025, 9216, 10816, 11025, 11664, 13456, 15129, 15625, 16641, 17689, 18496, 21609, 23409, 24649, 25600, 28561, 30276, 32761, 34596, 35721, 36100, 36864, 37636, 38025, 39204, 40000, 42436, 42849

Offset

1,1

Links

Peter Kagey, Table of n, a(n) for n = 1..1000

Example

36  = 6^2  = 1  + 35;
121 = 11^2 = 51 + 70;
196 = 14^2 = 51 + 145.

Prog

(PARI) is(k) = issquare(k) && sum(i=1, sqrt(1+12*k)\6, sqrt(1+24*k+12*i-36*i*i)%6==5)>0; \\ Jinyuan Wang, Mar 06 2020

Crossrefs

Cf. A000326, A332987, A332988, A333008, A333009.

Sequence in context: A271736 A280886 A278022 * A016862 A223506 A238037

Adjacent sequences: A333004 A333005 A333006 * A333008 A333009 A333010

Keyword

nonn,easy

Author

Olivier Gérard, Mar 05 2020

Extensions

More terms from Jinyuan Wang, Mar 06 2020

Status

approved