A069496 Smaller member of a twin prime pair with a square sum.

17, 71, 881, 1151, 2591, 3527, 4049, 15137, 20807, 34847, 46817, 69191, 83231, 103967, 112337, 149057, 176417, 179999, 206081, 281249, 362951, 388961, 438047, 472391, 478241, 538721, 649799, 734471, 808991, 960497, 1080449, 1143071

Offset: 1

Author

Amarnath Murthy, Mar 30 2002

Keywords

• nonn

Comments

All members of this sequence have digital root 8. - J. W. Helkenberg, Jul 24 2013

First bisection of A232878. - Gary Croft, Dec 05 2013

Examples

			71 is a term as the smaller member of the twin prime pair (71,73) as 71+73 = 144 = 12^2.
		

Links

• T. D. Noe, Table of n, a(n) for n = 1..10000
• Author?, Title? (no longer exists)

Crossrefs

Cf. A118593, A232878.

Programs

Maple

isa := n -> isprime(n) and isprime(n+2) and issqr(2*n+2):
select(isa, [$4..1000000]); # Peter Luschny, Jan 05 2020

Mathematica

First/@Select[Partition[Prime[Range[9*10^4]],2,1],Differences[#]=={2} && IntegerQ[Sqrt[Total[#]]] &] (* Jayanta Basu, May 26 2013 *)

PARI

t(n, p=3) = {while( p+2 < (p=nextprime( p+1 )) || n-->0, ); p-2}
for(n=1, 1e4, if(issquare(2*t(n)+2), print1(t(n), ", "))); \\ Altug Alkan, Mar 14 2016

Formula

a(n) = (A037072(n)-2)/2.

a(n) = A118593(n) - 2. - Zerinvary Lajos, Jul 31 2006

Extensions

More terms from Sascha Kurz, Apr 01 2002