A139220 Numbers k such that 41+(k+k^2)/2 = 41+A000217(k) is prime.

0, 3, 11, 20, 23, 27, 32, 39, 44, 48, 51, 56, 59, 60, 83, 104, 108, 111, 116, 128, 132, 135, 143, 171, 188, 203, 207, 212, 227, 240, 251, 263, 275, 296, 300, 312, 315, 324, 356, 359, 363, 380, 384, 392, 399, 408, 443, 447, 476, 479, 483, 504, 507, 515, 527, 528

Offset: 1

Author

Zak Seidov, Apr 11 2008

Keywords

• nonn

Comments

Corresponding values of primes are in A139219.

Numbers k such that both 41+(k+k^2)/2 and 41+(k+k^2) are primes, are in A139221.

Examples

			If k = 11 then 41 + (k + k^2) / 2 = 107 (prime).
		

Crossrefs

Cf. A000217, A056561, A139219, A139221.

Programs

Magma

[k:k in [0..530]| IsPrime(41+(k+k^2) div 2)]; // Marius A. Burtea, Feb 12 2020

Mathematica

Select[Table[Range[0,1000]],PrimeQ[41+(#+#^2)/2]&]

PARI

is(n)=isprime(n*(n+1)/2+41) \\ Charles R Greathouse IV, Aug 16 2015