A186073 - OEIS

A186073

Irregular triangle, read by rows, of primes with suffix n and digits "7" prepended, otherwise 0.

71, 0, 73, 773, 0, 0, 0, 0, 0, 79, 0, 0, 0, 0, 0, 0, 0, 0, 0, 719, 0, 0, 0, 0, 0, 0, 0, 727, 7727, 0, 0, 0, 0, 0, 733, 0, 0, 0, 0, 0, 739, 0, 0, 0, 743, 0, 0, 0, 0, 0, 0, 0, 751, 0, 0, 0, 0, 0, 757, 7757, 0, 0, 0, 761, 0, 0, 0, 0, 0, 0, 0, 769, 0, 0, 0, 773

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OFFSET

1,1

COMMENTS

Row n ends when a composite number is found.

LINKS

Table of n, a(n) for n=1..76.

EXAMPLE

for k=1..2 , a(3, k) = {73, 773} 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:=7*10^d+a0:if type(a1, prime)=true then a0:=a1:printf(`%d,