A186071 Irregular triangle, read by rows, of primes with suffix n and digits "3" prepended , otherwise 0.

31, 331, 3331, 33331, 333331, 3333331, 33333331, 0, 0, 0, 0, 0, 37, 337, 0, 0, 0, 311, 0, 313, 3313, 0, 0, 0, 317, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 331, 3331, 33331, 333331, 3333331, 33333331, 0, 0, 0, 0, 0, 337, 0, 0, 0, 0, 0, 0, 0, 0, 0, 347, 3347, 33347, 0, 349, 0, 0, 0, 353

Offset

1,1

Comments

Row n ends when a composite number is found.

Links

Table of n, a(n) for n=1..68.

Example

for k=1..7 , a(1, k) = {31, 331, 3331, 33331, 333331, 3333331, 33333331} are in the sequence.

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:d:=length(a0):a1:=3*10^d+a0: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:

Crossrefs

Cf. A185682, A185684, A185685, A185687.

Sequence in context: A362493 A029813 A138697 * A033175 A123568 A111675

Adjacent sequences: A186068 A186069 A186070 * A186072 A186073 A186074

Keyword

nonn,base,tabf

Author

Michel Lagneau, Feb 11 2011

Status

approved