OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..200
MATHEMATICA
a[1] = 9; a[n_] := a[n] = Block[{k = a[n - 1] + 1 + Mod[a[n - 1], 2], c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[ !PrimeQ[ FromDigits @ Flatten @ Append[c, IntegerDigits[k]]], k += 2]; k]; Table[ a[n], {n, 48}] (* Robert G. Wilson v *)
nxt[{j_, a_}]:=Module[{c=a+2}, While[CompositeQ[j*10^IntegerLength[c]+c], c+=2]; {j*10^IntegerLength[c]+c, c}]; NestList[nxt, {9, 9}, 50][[All, 2]] (* Harvey P. Dale, Jan 26 2022 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Sep 23 2002
EXTENSIONS
Corrected and extended by Robert G. Wilson v, Aug 05 2005
STATUS
approved