A056897 Smallest square where a(n)+n is prime.

1, 0, 0, 1, 0, 1, 0, 9, 4, 1, 0, 1, 0, 9, 4, 1, 0, 1, 0, 9, 16, 1, 0, 49, 4, 81, 4, 1, 0, 1, 0, 9, 4, 9, 36, 1, 0, 9, 4, 1, 0, 1, 0, 9, 16, 1, 0, 25, 4, 9, 16, 1, 0, 25, 4, 81, 4, 1, 0, 1, 0, 9, 4, 9, 36, 1, 0, 81, 4, 1, 0, 1, 0, 9, 4, 25, 36, 1, 0, 9, 16, 1, 0, 25, 4, 81, 16, 1, 0, 49, 16, 9, 4, 9

Offset: 0

Author

Henry Bottomley, Jul 05 2000

Keywords

• nonn

Examples

			a(8)=9 since 9 is a square and 9+8=7 which is a prime
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A000040, A002496, A056892-A056898.

Programs

Mathematica

With[{sqs=Range[0,20]^2},Table[SelectFirst[sqs,PrimeQ[n+#]&],{n,100}]] (* The program uses the SelectFirst function from Mathematica version 10 *) (* Harvey P. Dale, May 07 2016 *)

Formula

a(n) =A056896(n)-n =A056898(n)^2