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

0, 3, 11, 20, 23, 27, 32, 39, 48, 51, 59, 60, 83, 108, 111, 116, 128, 132, 135, 171, 188, 203, 212, 227, 240, 263, 275, 315, 324, 356, 359, 363, 384, 392, 447, 476, 479, 515, 528, 588, 627, 647, 648, 672, 731, 759, 780, 804, 839, 864, 875, 900, 903, 968, 975

Offset

1,2

Comments

Intersection of A139220 and A056561.

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Example

If k = 11 then 41 + (k + k^2) / 2 = 107 (prime) and 41 + (k + k^2) = 173 (prime).

Mathematica

Select[Table[Range[0, 2000]], PrimeQ[41+(#+#^2)/2]&&PrimeQ[41+#+#^2]&]

Prog

(Magma) [k:k in [0..1000]| IsPrime(41+(k+k^2) div 2) and IsPrime(41+k+k^2)]; // Marius A. Burtea, Feb 12 2020
(PARI) for(n=0, 1000, if(isprime(binomial(n+1, 2) +41) && isprime(n^2+n+41), print1(n", "))) \\ G. C. Greubel, Feb 12 2020
(Sage) [n for n in (0..1000) if is_prime(binomial(n+1, 2)+41) and is_prime(n^2+n+41)] # G. C. Greubel, Feb 12 2020

Crossrefs

Cf. A000217, A056561, A139219, A139220.

Sequence in context: A279257 A166096 A139220 * A300381 A363012 A006876

Adjacent sequences: A139218 A139219 A139220 * A139222 A139223 A139224

Keyword

nonn

Author

Zak Seidov, Apr 11 2008

Status

approved