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

1,1

Links

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

Example

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.

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 + #]]]] &]

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).

Sequence in context: A045455 A160031 A154634 * A175866 A227500 A265814

Adjacent sequences: A232652 A232653 A232654 * A232656 A232657 A232658

Keyword

nonn,base,less

Author

K. D. Bajpai, Nov 27 2013

Status

approved