A167737 Primes that become squares when prefixed with a 4.

41, 761, 23801, 31649, 39569, 63761, 1100921, 1951529, 2497361, 2810849, 3046721, 3678881, 4715969, 4796249, 5118089, 5198729, 5441081, 5846441, 5927729, 6009089, 6498761, 6662561, 6908801, 7238129, 7983329, 8149721, 8483369, 8734361, 9744809, 9829481

Offset: 1

Author

Claudio Meller, Nov 10 2009

Keywords

• base
• nonn
• changed

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A167734, A167735, A167736, A167738, A167739, A167740, A167741.

Programs

Maple

map(t -> t - 4*10^ilog10(t), select(t -> isprime(t - 4*10^ilog10(t)), [seq(seq(i^2,i=ceil(sqrt(4.1*10^d)) .. floor(sqrt(5*10^d))),d=1..10)])); # Robert Israel, Nov 08 2023

Mathematica

Select[Prime[Range[10^4]], IntegerQ[Sqrt[FromDigits[Join[{4}, IntegerDigits[#]]]]]&] (* G. C. Greubel, Jun 23 2016 *)

Extensions

More terms from Michel Marcus, Aug 05 2013