A168550 - OEIS

%I #15 Jan 13 2022 13:25:22

%S 1,2,5,6,9,11,12,20,21,26,27,29,30,32,35,44,57,59,60,71,72,77,86,92,

%T 95,96,99,107,111,120,134,140,149,150,152,159,162,164,165,170,185,186,

%U 191,192,197,204,221,227,231,237,246,249,252,260,264,266,269,275,290,297

%N Natural numbers k for which 1 + 2*k^3 is prime.

%H Zak Seidov, <a href="/A168550/b168550.txt">Table of n, a(n) for n = 1..1000</a>

%e 20 is a term because 1 + 2*20^3 = 16001 is prime.

%p isA168550 := proc(n) isprime(1+2*n^3) ; end proc: for n from 1 to 400 do if isA168550(n) then printf("%d,",n) ; end if; end do: # _R. J. Mathar_, Nov 30 2009

%t Select[Range[300],PrimeQ[1+2#^3]&] (* _Harvey P. Dale_, Jan 13 2022 *)

%Y Cf. A201107, A033562, A049408.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Nov 29 2009

%E Terms beyond 21 from _R. J. Mathar_, Nov 30 2009

%E Example corrected by _Jon E. Schoenfield_, May 11 2019