A117819 - OEIS

A117819

Final digit d of n is in the sequence iff d is prime or n is prime.

2, 3, 5, 7, 1, 2, 3, 5, 7, 9, 2, 3, 5, 7, 9, 1, 2, 3, 5, 7, 1, 2, 3, 5, 7, 2, 3, 5, 7, 9, 1, 2, 3, 5, 7, 1, 2, 3, 5, 7, 9, 2, 3, 5, 7, 9, 2, 3, 5, 7, 1, 2, 3, 5, 7, 9, 2, 3, 5, 7, 2, 3, 5, 7, 1, 2, 3, 5, 7, 9, 2, 3, 5, 7, 9, 1, 2, 3, 5, 7, 2, 3, 5, 7, 2, 3, 5, 7, 9, 1, 2, 3, 5, 7, 1, 2, 3, 5, 7, 9, 2, 3, 5, 7, 1

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..105.

EXAMPLE

Calculations:

n: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ...

d: - 2 3 - 5 - 7 - - -- -1 -2 -3 -- -5 -- -7 -- -9 -- ...

MATHEMATICA

Table[If[PrimeQ[n]||PrimeQ[Mod[n, 10]], Mod[n, 10], Nothing], {n, 300}] (* Harvey P. Dale, Oct 03 2016 *)

PROG