A232655 Primes p such that reversal (p^2+p) is also prime.

5, 13, 19, 103, 139, 181, 193, 271, 277, 313, 379, 433, 577, 619, 631, 853, 859, 883, 1093, 1117, 1123, 1237, 1279, 1321, 1741, 1873, 1933, 1987, 2659, 2707, 2713, 2719, 2767, 2791, 3163, 3217, 3271, 3331, 3469, 3529, 3547, 3631, 3637, 3727, 3907, 3943, 4129, 4177

Offset: 1

Author

K. D. Bajpai, Nov 27 2013

Keywords

• nonn
• base
• less

Examples

			a(2)= 13, it is prime: n= 6, prime(6)= 13: reversal(13^2+13)= 281, which is also prime.
a(4)= 103, it is prime: n= 27, prime(27)= 103: reversal(103^2+103)= 21701, which is also prime.
a(6)= 181, it is prime: n= 42, prime(42)= 181: reversal(181^2+181)= 24923, which is also prime.
		

Links

• K. D. Bajpai, Table of n, a(n) for n = 1..6650

Crossrefs

Cf. A004087 (primes written backwards).

Cf. A061783 (primes p: p+(p reversed)is also prime).

Cf. A232446 (primes p: reversal(p^2)+p is also prime).

Programs

Maple

with(StringTools): KD:= proc() local a, p; p:=ithprime(n); a:= parse(Reverse(convert((p^2+p), string))); if isprime(a) then RETURN (p): fi; end: seq(KD(), n=1..3000);

Mathematica

Select[Prime[Range[3000]], PrimeQ[FromDigits[Reverse[IntegerDigits[#^2 + #]]]] &]