A120535 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Semiprime analog of A117065.

LINKS

Table of n, a(n) for n=1..48.

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 *)

CROSSREFS

A001358 intersect A003679.

Cf. A001358, A003679, A117065.

Sequence in context: A334261 A290434 A230834 * A146948 A033944 A287143

Adjacent sequences: A120532 A120533 A120534 * A120536 A120537 A120538

KEYWORD

fini,full,nonn

AUTHOR

Jonathan Vos Post, Aug 06 2006

EXTENSIONS

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

STATUS

approved