A120535 Semiprimes that are not the sum of 3 pentagonal numbers.

4, 9, 21, 26, 33, 38, 55, 65, 77, 111, 142, 159, 166, 183, 205, 217, 226, 265, 346, 371, 395, 417, 453, 551, 573, 597, 655, 681, 843, 905, 951, 985, 1059, 1165, 1441, 1563, 2033, 2073, 2126, 2361, 2487, 2841, 2991, 3831, 4061, 4601, 8691, 10911

Offset: 1

Author

Jonathan Vos Post, Aug 06 2006

Keywords

• fini
• full
• nonn

Comments

Semiprime analog of A117065.

Crossrefs

A001358 intersect A003679.

Cf. A001358, A003679, A117065.

Programs

Mathematica

v = #*(3*#-1)/2& @ Range[0, 90]; Select[ Complement[ Range[0, 11000], Union[Total /@ Tuples[{v, v, v}]]], PrimeOmega[#] == 2 &] (* Giovanni Resta, Jun 13 2016 *)

Extensions

Missing a(39) = 2126 from Giovanni Resta, Jun 13 2016