A173446 ((n+{0,1})-th prime-1)^2+1 are both primes.

1, 2, 3, 4, 12, 31, 36, 53, 54, 78, 82, 105, 125, 155, 247, 403, 422, 548, 678, 679, 751, 769, 784, 798, 809, 829, 845, 899, 1049, 1148, 1155, 1312, 1317, 1423, 1436, 1490, 1616, 1688, 1935, 1961, 1990, 1991, 2071, 2181, 2198, 2397, 2437, 2454, 2463, 2556

Offset

1,2

Comments

Numbers n such that ((n+{0,1})-th prime-1)^2+1 are both primes.

Links

Table of n, a(n) for n=1..50.

Example

a(1)=1 because ((1+0)-th prime-1)^2+1=2=prime and ((1+1)-th prime-1)^2+1=5=prime; a(2)=2 because ((2+0)-th prime-1)^2+1=5=prime and ((2+1)-th prime-1)^2+1=17=prime

Crossrefs

Cf. A000040, A006093, A127435, A173444.

Sequence in context: A168047 A236371 A333620 * A053350 A165302 A276530

Adjacent sequences: A173443 A173444 A173445 * A173447 A173448 A173449

Keyword

nonn

Author

Juri-Stepan Gerasimov, Feb 18 2010

Extensions

126 removed. Terms beyond 247 added by R. J. Mathar, Mar 01 2010

Status

approved