OFFSET
1,1
COMMENTS
It is conjectured that are just 3 palindromic primes with digit sum 2, namely 2, 11 and 101. If any others exist, they must be of the form 10^(2^k) +1 with k > 14.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..238
Hans Riesel, Some factors of the numbers Gn = 6^2^n+1 and Hn = 10^2^n+1, Math. Comp. 23 (1969), p. 413-415. With errata reported in Math. Comp. 24 (1970), p. 243.
MATHEMATICA
Do[p = Join[ IntegerDigits[n, 4], Reverse[ Drop[ IntegerDigits[n, 4], -1]]]; q = Plus @@ p; If[q == 5 && PrimeQ[ FromDigits[p]] && q == 5, Print[ FromDigits[p]]], {n, 1, 4 10^8}] (* this coding will not pick up the first entry *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, May 05 2002
EXTENSIONS
Edited by Robert G. Wilson v, May 15 2002
STATUS
approved