A185687 Irregular triangle, read by rows, of primes with prefix n and digits "9" appended, otherwise 0.

19, 199, 1999, 29, 0, 0, 59, 599, 0, 79, 89, 0, 109, 0, 0, 139, 1399, 13999, 139999, 1399999, 149, 1499, 0, 0, 179, 0, 199, 1999, 0, 0, 229, 239, 2399, 0, 0, 269, 2699, 0, 0, 0, 0, 0, 0, 0, 349, 3499, 359, 0, 379, 389, 0, 409, 4099, 419, 0, 439, 449, 0, 0, 479, 4799, 0, 499, 4999, 49999, 509, 5099, 0, 0, 0, 0, 0, 569, 0, 0, 599, 0, 619

Offset

1,1

Comments

Row n ends when a composite number is found.

Links

Table of n, a(n) for n=1..78.

Example

for k = 1..6, a(608, k) = { 6089, 60899, 608999,6089999,60899999,608999999}
  are in the sequence.
19,199,1999;
29;
0;
0;
59,599;
0;
79;
89;
0;
109;
0;
0;
139,1399,13999,139999,1399999;
149,1499;

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+9: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, 9]]; PrimeQ[p], cnt++; Sow[p]]; If[cnt == 0, Sow[0]], {n, 61}]][[2, 1]]

Crossrefs

Cf. A185682, A185684, A185685.

Sequence in context: A066007 A147830 A135162 * A067272 A065582 A241021

Adjacent sequences: A185684 A185685 A185686 * A185688 A185689 A185690

Keyword

nonn,base,tabf,less

Author

Michel Lagneau, Feb 10 2011

Status

approved