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A186071 Irregular triangle, read by rows, of primes with suffix n and digits "3" prepended , otherwise 0. 3
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 (list; graph; refs; listen; history; text; internal format)
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: A221189 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

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Last modified January 20 08:18 EST 2020. Contains 331081 sequences. (Running on oeis4.)