A230199 Sum of digits of n-th palindromic prime.

2, 3, 5, 7, 2, 2, 5, 7, 10, 11, 7, 11, 13, 14, 16, 19, 22, 23, 19, 20, 5, 7, 8, 7, 8, 10, 13, 14, 11, 16, 17, 13, 17, 16, 17, 14, 17, 19, 20, 20, 25, 19, 22, 23, 28, 29, 7, 8, 10, 13, 14, 8, 13, 13, 14, 17, 19, 22, 16, 17, 19, 23, 20, 23, 22, 25, 22, 23, 29

Offset: 1

Author

Shyam Sunder Gupta, Oct 11 2013

Keywords

• nonn
• base
• less

Examples

			a(6) =2, since sum of digits of 6th palindromic prime i.e. 101 is 2.
		

Links

• Shyam Sunder Gupta, Table of n, a(n) for n = 1..5953

Crossrefs

Cf. A002385, A007953, A007605.

Programs

Mathematica

a = {}; Do[z = n*10^(IntegerLength[n] - 1) +
FromDigits@Rest@Reverse@IntegerDigits[n]; If[PrimeQ[z], s = Apply[Plus, IntegerDigits[z]]; AppendTo[a, s]], {n, 1, 10^5}]; Insert[a, 2, 5]
palQ[n_]:=Module[{idn=IntegerDigits[n]},idn==Reverse[idn]]; Total[ IntegerDigits[ #]]&/@ Select[Prime[Range[5000]],palQ] (* Harvey P. Dale, Oct 10 2014 *)

Formula

a(n) = A007953(A002385(n)). - R. J. Mathar, Sep 09 2015