

A075766


Numbers n such that A007923(n) is prime.


0



2, 7, 8, 10, 17, 20, 25, 28, 31, 38, 61, 62, 355, 4690, 4772
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OFFSET

1,1


COMMENTS

SDS(355) certified prime with Primo.
No more terms <= 8000.  XU Pingya, May 30 2017


LINKS

Table of n, a(n) for n=1..15.
J. Earls, Some Results Concerning the Smarandache Deconstructive Sequence, Smarandache Notions Journal, Volume 14 Issue 1, January 2004, Pages 222226 .


PROG

(PARI) isok(n) = my(m=(n*(n+1)/21)%9+1); isprime(sum(k=0, n1, 10^k*((mk1)%9+1))); \\ Michel Marcus, May 30 2017


CROSSREFS

Cf. A007923.
Sequence in context: A039005 A022431 A047525 * A258823 A226612 A005538
Adjacent sequences: A075763 A075764 A075765 * A075767 A075768 A075769


KEYWORD

more,nonn


AUTHOR

Jason Earls, Oct 09 2002


EXTENSIONS

a(14)a(15) from XU Pingya, May 30 2017


STATUS

approved



