A241659 - OEIS

A241659

Primes p such that p^3 + 2 is semiprime.

2, 11, 13, 17, 19, 23, 31, 41, 53, 59, 89, 101, 131, 137, 149, 193, 211, 223, 227, 229, 233, 239, 251, 271, 293, 317, 331, 359, 401, 449, 461, 557, 563, 571, 593, 599, 619, 641, 659, 677, 691, 719, 739, 751, 809, 821, 853, 929, 971, 991, 1009, 1013, 1039, 1051

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

OFFSET

1,1

LINKS

K. D. Bajpai, Table of n, a(n) for n = 1..10000

EXAMPLE

11 is prime and appears in the sequence because 11^3 + 2 = 1333 = 31 * 43, which is a semiprime.

17 is prime and appears in the sequence because 17^3 + 2 = 4915 = 5 * 983, which is a semiprime.

37 is prime but does not appear in the sequence because 37^3 + 2 = 50655 = 3 * 5 * 11 * 983, which is not a semiprime.

MAPLE

with(numtheory): KD:= proc() local a, b, k; k:=ithprime(n); a:=bigomega(k^3+2); if a=2 then RETURN (k); fi; end: seq(KD(), n=1..500);

MATHEMATICA

A241659 = {}; Do[t = Prime[n]; If[PrimeOmega[t^3 + 2] == 2, AppendTo[A241659, t]], {n, 500}]; A241659

(*For the b-file*) c = 0; Do[t = Prime[n]; If[PrimeOmega[t^3 + 2] == 2, c++; Print[c, " ", t]], {n, 1, 6*10^4}];

PROG

(PARI) s=[]; forprime(p=2, 1200, if(bigomega(p^3+2)==2, s=concat(s, p))); s \\ Colin Barker, Apr 27 2014

CROSSREFS

Cf. A001358, A063637, A063638, A228183, A237627, A241483, A241493.

Sequence in context: A048521 A172071 A058048 * A038915 A166849 A119449

Adjacent sequences: A241656 A241657 A241658 * A241660 A241661 A241662

KEYWORD

nonn

AUTHOR

K. D. Bajpai, Apr 26 2014

STATUS

approved