OFFSET
1,1
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..439
MATHEMATICA
a[1] = 6; 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[{k=a+2}, While[CompositeQ[j(10^ IntegerLength[ k])+k], k+=2]; {j(10^IntegerLength[k])+k, k}]; Join[{6}, NestList[ nxt, {67, 7}, 50][[All, 2]]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 19 2021 *)
PROG
(Python)
from sympy import isprime
def aupton(terms):
alst, astr = [6], "6"
for n in range(2, terms+1):
an = alst[-1] + 1
while not isprime(int(astr+str(an))): an += 1
alst, astr = alst + [an], astr + str(an)
return alst
print(aupton(62)) # Michael S. Branicky, Jun 07 2021
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Sep 23 2002
EXTENSIONS
Corrected and extended by Robert G. Wilson v, Aug 05 2005
STATUS
approved