login
A232446
Primes p such that reversal( p^2 ) + p is also prime.
2
7, 151, 787, 1549, 1579, 2029, 2083, 2179, 2833, 2971, 4549, 4591, 4801, 4999, 5077, 5167, 5179, 5209, 5227, 5407, 6343, 6529, 6547, 6553, 6577, 6679, 7027, 7753, 7867, 7873, 7927, 7963, 7993, 8167, 8191, 8311, 9091, 9103, 9151, 9283, 14251, 14281, 14389, 14437
OFFSET
1,1
LINKS
EXAMPLE
a(1)= 7, it is prime: prime(4)= 7: reversal(7^2)+7= reversal(49)+7= 94+7= 101 which is also prime.
a(2)= 151, it is prime: prime(36)= 151: reversal(151^2)+151= reversal(22801)+151=10822+151= 10973 which is also prime.
MAPLE
with(StringTools): KD:= proc() local a, p; p:=ithprime(n); a:= parse(Reverse(convert((p^2), string)))+p; 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. A061783 (primes p: p+(p reversed) is also prime).
Function reversal is given by A004086. Cf. also A004087.
Sequence in context: A309855 A364845 A339582 * A362491 A202558 A159659
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Nov 24 2013
STATUS
approved