OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..48
MATHEMATICA
NextComposite[n_] := Block[{k = n + 1}, While[PrimeQ[k], k++ ]; k]; f[n_] := Block[{b = 2}, While[b < n && !PrimeQ[ FromDigits[ Reverse[ IntegerDigits[n, b]], b]], b++ ]; b]; If[b != n, b, 0]; b = -1; k = 4; Do[ While[c = f[k]; c <= b, k = NextComposite[k]]; b = c; Print[k], {n, 1, 31}]
CROSSREFS
KEYWORD
base,hard,nonn
AUTHOR
Robert G. Wilson v, Sep 09 2002
EXTENSIONS
More terms from Amiram Eldar, Jun 04 2021
STATUS
approved