

A296029


Numbers k such that 10^k/8  1 is prime.


1



4, 7, 8, 11, 16, 22, 28, 29, 79, 91, 170, 293, 392, 1898, 2597, 3641, 4099, 8236, 11393, 17969, 18503
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OFFSET

1,1


COMMENTS

Searched up to k=20000.  Michael B. Porter, Dec 07 2017
Equivalently, numbers k such that 125*10^(k3)  1 is prime.


LINKS

Table of n, a(n) for n=1..21.


EXAMPLE

1249, 1249999, and 12499999 are prime, so 4, 7, and 8 are in the sequence.


MATHEMATICA

Select[Range[2000], PrimeQ[10^#/8  1] &] (* Michael De Vlieger, Dec 08 2017 *)


PROG

(PARI) lista(nn) = for(n=4, nn, if(ispseudoprime(10^n/8  1), print1(n, ", "))) \\ Iain Fox, Dec 04 2017


CROSSREFS

Sequence in context: A137362 A190765 A024621 * A000606 A215458 A061932
Adjacent sequences: A296026 A296027 A296028 * A296030 A296031 A296032


KEYWORD

nonn,more


AUTHOR

Patrick A. Thomas, Dec 03 2017


EXTENSIONS

a(12), a(13), a(15), a(16) from Jon E. Schoenfield, Dec 03 2017
a(14) and a(17)a(21) from Michael B. Porter, Dec 07 2017


STATUS

approved



