OFFSET
1,1
COMMENTS
Row n ends when a composite number is found.
No row has more than two terms. - Robert Israel, Sep 06 2024
EXAMPLE
For k=1..2, a(15, k) = {151, 1511} are in the sequence.
Triangle begins:
11;
0;
31, 311;
41;
0;
61;
71;
0;
0;
101;
...
MAPLE
with(numtheory): for n from 1 to 100 do:a0:=n:id:=0:c:=0:for k from 1 to 20
while (id=0) do:a1:=a0*10+1:if type(a1, prime)=true then a0:=a1:printf(`%d, `, a0):c:=c+1:else
id:=1:fi:od:if c=0 then printf(`%d, `, 0):else fi:od:~
MATHEMATICA
Reap[Do[cnt = 0; d = IntegerDigits[n]; While[p = FromDigits[AppendTo[d, 1]]; PrimeQ[p], cnt++; Sow[p]]; If[cnt == 0, Sow[0]], {n, 61}]][[2, 1]]
CROSSREFS
KEYWORD
nonn,base,less,tabf
AUTHOR
Michel Lagneau, Feb 10 2011
STATUS
approved