OFFSET
2,1
COMMENTS
These are the values of n+k from A341715. See that entry for more information.
See A084559 (the same for nonprime indices) for further information. - M. F. Hasler, Feb 22 2021
Suppose n > 3. If n == 2 (mod 3), then a(n) == 3 or 5 (mod 6). If n = 0 or 1 (mod 3), then a(n) == 1 (mod 6) (see A341716). - Chai Wah Wu, Feb 22 2021
FORMULA
a(n) = n iff n is prime, otherwise a(n) = A084559(n). - M. F. Hasler, Feb 22 2021
MATHEMATICA
Array[Block[{k = #, s = #}, While[! PrimeQ[s], k++; s = FromDigits[IntegerDigits[s]~Join~IntegerDigits[k]]]; k] &, 8, 2] (* Michael De Vlieger, Feb 22 2021 *)
PROG
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
N. J. A. Sloane, Feb 22 2021
STATUS
approved