OFFSET
2,1
COMMENTS
The corresponding indices of the decimal digit 1 are 1, 1, 1, 5, 1, 7, 1, 0, 2, 6, 3, 3, 11, 2, 14, 4, 0, 4, 6, 0, 4, ... (A241018).
LINKS
Michel Lagneau, Table of n, a(n) for n = 2..150
MAPLE
with(numtheory):nn:=80:T:=array(1..nn):
for n from 2 to nn do:
for i from 1 to n do:
T[i]:=9:
od:
ii:=0:
for j from 1 to n while(ii=0)do:
T[j]:=1:s:=sum('T[i]*10^(n-i)', 'i'=1..n):
if type(s, prime)=true
then
ii:=1: printf(`%d, `, s):
else
T[j]:=9:
fi:
od:
if ii=0
then
printf(`%d, `, 0):
else
fi:
od:
MATHEMATICA
Table[SelectFirst[FromDigits/@Table[Insert[PadRight[{}, k, 9], 1, n], {n, k+1}], PrimeQ], {k, 30}]/.Missing["NotFound"]->0 (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 10 2017 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Lagneau, Apr 15 2014
STATUS
approved