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A181732 Numbers n such that 90n + 1 is prime. 26
2, 3, 6, 7, 9, 11, 13, 17, 18, 20, 24, 25, 26, 28, 31, 33, 34, 37, 39, 41, 45, 47, 51, 54, 55, 62, 65, 68, 69, 70, 72, 73, 74, 76, 84, 86, 89, 90, 91, 94, 96, 97, 98, 100, 101, 102, 107, 108, 109, 110, 117, 119, 121, 123, 124, 125, 130, 133, 136, 138, 139, 140 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = (1/90) [A142312(n) - 1].

a(n) ~ (4/15) n log n. - Charles R Greathouse IV, Jun 01 2016, corrected Sep 05 2016

MAPLE

a:= proc(n) option remember; local k;

       for k from 1+ `if`(n=1, 1, a(n-1))

       while not isprime(90*k+1) do od; k

    end:

seq(a(n), n=1..100);  # Alois P. Heinz, Dec 05 2011

MATHEMATICA

Select[Range[200], PrimeQ[90 # + 1] &] (* Vincenzo Librandi, Sep 06 2016 *)

PROG

(PARI) is(n)=n%90==1 && isprime(n) \\ Charles R Greathouse IV, Jun 01 2016

(MAGMA) [n: n in [0..200]| IsPrime(90*n+1)]; // Vincenzo Librandi, Sep 06 2016

CROSSREFS

Cf. A142312. Complement of A255491.

Sequence in context: A259726 A259587 A304107 * A190199 A014873 A029467

Adjacent sequences:  A181729 A181730 A181731 * A181733 A181734 A181735

KEYWORD

nonn,easy

AUTHOR

J. W. Helkenberg, Nov 16 2010

EXTENSIONS

New name from Michael B. Porter, Jul 26 2013

STATUS

approved

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Last modified August 15 00:24 EDT 2020. Contains 336484 sequences. (Running on oeis4.)