1,1

This is the intersection of A028873 and A005574; this sequence is also a subset of A090120 (n such that closest primes above and below n^2 differ by 4).

Table of n, a(n) for n=1..47.

a(2)=10 since 10^2 + 1 = 101 and 10^2 - 3 = 97 are both prime.

(MAGMA) [n: n in [2..100000] |IsPrime(n^2+1) and IsPrime(n^2-3)] // Vincenzo Librandi, Nov 13 2010

Cf. A005574, A028873, A090120.

Sequence in context: A310421 A310422 A310423 * A302087 A099355 A161366

Adjacent sequences: A114332 A114333 A114334 * A114336 A114337 A114338

nonn

John L. Drost, Feb 07 2006

approved