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

Author

Olivier Gérard, Mar 05 2020

Keywords

• nonn
• easy

Examples

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

Links

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

Crossrefs

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

Programs

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

Extensions

More terms from Jinyuan Wang, Mar 06 2020