A086924 Primes such that sum of the first and last digits is a square.

2, 13, 31, 79, 97, 103, 113, 163, 173, 193, 227, 257, 277, 311, 331, 613, 643, 653, 673, 683, 709, 719, 739, 769, 811, 821, 881, 907, 937, 947, 967, 977, 997, 1013, 1033, 1063, 1093, 1103, 1123, 1153, 1163, 1193, 1213, 1223

Offset: 1

Author

Zak Seidov, Sep 20 2003

Keywords

• easy
• nonn
• base

Crossrefs

Cf. A088133, A088134, A088135, A088136.

Programs

Mathematica

fldsQ[n_]:=Module[{idn=IntegerDigits[n]},IntegerQ[Sqrt[ idn[[1]] + idn[[-1]]]]]; Select[Prime[Range[200]],fldsQ] (* Harvey P. Dale, Aug 12 2017 *)

PARI

okdigs(n) = digs = digits(n); issquare(digs[1]+digs[#digs]);
isok(n) = isprime(n) && okdigs(n); \\ Michel Marcus, Oct 05 2013