OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
4^2=16, reversed is 61. 16+61=77 which is semiprime (7*11), so 4 is in this sequence.
MAPLE
revdigs:= proc(n) local L, i;
L:= convert(n, base, 10);
add(L[-i]*10^(i-1), i=1..nops(L))
end proc:
filter:= proc(n) local a, b;
a:= n^2;
b:= revdigs(a);
isprime(b) and numtheory:-bigomega(a+b)=2
end proc:
select(filter, [$1..10000]); # Robert Israel, Mar 31 2019
MATHEMATICA
Select[Range[50000],
PrimeQ[IntegerReverse[#^2]] &&
PrimeOmega[#^2 + IntegerReverse[#^2]] == 2 &]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Robert Price, Mar 31 2019
STATUS
approved