A185684 Irregular triangle, read by rows, of primes with prefix n and digits "3" appended, otherwise 0.

13, 23, 233, 2333, 23333, 0, 43, 433, 53, 0, 73, 733, 7333, 83, 0, 103, 1033, 10333, 103333, 113, 0, 0, 0, 0, 163, 173, 1733, 17333, 0, 193, 1933, 19333, 0, 0, 223, 233, 2333, 23333, 0, 0, 263, 2633, 0, 283, 2833, 293, 0, 313, 0, 0, 0, 353, 3533, 0, 373, 3733, 383, 3833, 38333

Offset

1,1

Comments

Row n ends when a composite number is found.

Links

Table of n, a(n) for n=1..59.

Example

In row n=2, for k=1..4, a(2,k) = {23, 233, 2333, 23333} are in the table.

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+3: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, 3]]; PrimeQ[p], cnt++; Sow[p]]; If[cnt == 0, Sow[0]], {n, 61}]][[2, 1]] (* T. D. Noe, Feb 10 2011 *)

Crossrefs

Cf. A185682

Sequence in context: A299361 A089768 A300602 * A018945 A018958 A119410

Adjacent sequences: A185681 A185682 A185683 * A185685 A185686 A185687

Keyword

nonn,base,less,tabf

Author

Michel Lagneau, Feb 10 2011

Status

approved