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A075766 Numbers k such that A007923(k) is prime. 0
2, 7, 8, 10, 17, 20, 25, 28, 31, 38, 61, 62, 355, 4690, 4772, 8162, 10523, 14716 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
SDS(355) certified prime with Primo.
No more terms <= 8000. - XU Pingya, May 30 2017
LINKS
Jason Earls, Some Results Concerning the Smarandache Deconstructive Sequence, Smarandache Notions Journal, Volume 14 Issue 1, January 2004, Pages 222-226 .
PROG
(PARI) isok(n) = my(m=(n*(n+1)/2-1)%9+1); isprime(sum(k=0, n-1, 10^k*((m-k-1)%9+1))); \\ Michel Marcus, May 30 2017
CROSSREFS
Cf. A007923.
Sequence in context: A022431 A356671 A047525 * A258823 A226612 A005538
KEYWORD
more,nonn
AUTHOR
Jason Earls, Oct 09 2002
EXTENSIONS
a(14)-a(15) from XU Pingya, May 30 2017
a(16)-a(18) from Michael S. Branicky, Jun 22 2023
STATUS
approved

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Last modified April 14 18:28 EDT 2024. Contains 371667 sequences. (Running on oeis4.)