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A175727 Numbers n such that both A000203(n)-n-1 and A000203(n)-2*n-1 are prime numbers. 2
30, 42, 60, 70, 78, 102, 138, 186, 198, 216, 222, 228, 240, 246, 258, 270, 282, 360, 372, 390, 414, 438, 492, 498, 546, 582, 600, 606, 642, 708, 720, 756, 762, 774, 786, 810, 852, 870, 930, 942, 954, 1002, 1014, 1020, 1026, 1038, 1068, 1086, 1182, 1266, 1290 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A simpler version of A179945, added at the request of the editor-in-chief.

LINKS

Table of n, a(n) for n=1..51.

PROG

(PARI) is(n)=my(s=sigma(n)); isprime(s-n-1) && isprime(s-n-n-1) \\ Charles R Greathouse IV, Feb 19 2013

CROSSREFS

Subsequence of A179945.

Sequence in context: A033992 A214195 A091454 * A179945 A136152 A244066

Adjacent sequences:  A175724 A175725 A175726 * A175728 A175729 A175730

KEYWORD

nonn

AUTHOR

Max Alekseyev, Aug 18 2010

EXTENSIONS

Edited by N. J. A. Sloane, Aug 28 2010

STATUS

approved

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Last modified March 30 20:18 EDT 2017. Contains 284302 sequences.