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

1,1

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

Links

T. D. Noe, Table of n, a(n) for n = 1..10000

Author?, Title? (no longer exists)

Formula

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

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

Example

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

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 *)

Prog

(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

Crossrefs

Cf. A118593, A232878.

Sequence in context: A290243 A320895 A288748 * A047978 A050524 A214530

Adjacent sequences: A069493 A069494 A069495 * A069497 A069498 A069499

Keyword

nonn

Author

Amarnath Murthy, Mar 30 2002

Extensions

More terms from Sascha Kurz, Apr 01 2002

Status

approved