A252005 a(1)=2; for n>1, a(n) is the least prime > a(n-1) such that sum of digits of a(n-1) and a(n) is prime.

2, 3, 11, 23, 53, 83, 101, 113, 149, 179, 239, 269, 293, 311, 347, 359, 383, 401, 419, 449, 479, 557, 563, 593, 617, 647, 653, 683, 743, 773, 839, 863, 929, 953, 983, 1019, 1061, 1091, 1151, 1163, 1223, 1301, 1319, 1367, 1373, 1439, 1481, 1493, 1553, 1583, 1607, 1619, 1667, 1697, 1733, 1787, 1823

Offset

1,1

Links

Zak Seidov, Table of n, a(n) for n = 1..1000

Example

a(2)=3, next primes are 5, 7, 11 and only 3+1+1 is prime, hence
a(3)=11, next primes are 13, 17, 19, 23 and only 1+1+2+3 is prime, hence a(4)=23, etc.

Mathematica

lp[n_]:=Module[{p=NextPrime[n], tid=Total[IntegerDigits[n]]}, While[ CompositeQ[ Total[ IntegerDigits[p]]+tid], p=NextPrime[p]]; p]; NestList[ lp, 2, 60] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 30 2018 *)

Crossrefs

Cf. A007953, A252006.

Sequence in context: A263729 A246496 A119641 * A074496 A292817 A292112

Adjacent sequences: A252002 A252003 A252004 * A252006 A252007 A252008

Keyword

base,nonn

Author

Zak Seidov, Dec 12 2014

Status

approved