OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(3) = 37 is a term because 37 is prime, the next prime is 41, 37*41 = 1517 and its digit reversal 7151 is prime.
MAPLE
revdigs:= proc(n) local L, i;
L:= convert(n, base, 10);
add(L[-i]*10^(i-1), i=1..nops(L))
end proc:
P:= [seq(ithprime(i), i=1..1000)]:
P[select(i -> isprime(revdigs(P[i]*P[i+1])), [$1..999])];
MATHEMATICA
a354881[n_] := Select[Map[Prime, Range[n]], PrimeQ[FromDigits[Reverse[IntegerDigits[# NextPrime[#]]]]]&]
a354881[390] (* Hartmut F. W. Hoft, Jul 20 2022 *)
Select[Partition[Prime[Range[400]], 2, 1], PrimeQ[IntegerReverse[Times@@#]]&][[;; , 1]] (* Harvey P. Dale, Feb 10 2024 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
J. M. Bergot and Robert Israel, Jul 13 2022
STATUS
approved