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A105421 Numbers n such that prime(n + 1) == 7 (mod n). 1
1, 2, 3, 4, 8, 30, 31, 33, 68, 72, 180, 1052, 6471, 40083, 40087, 40090, 40113, 40120, 100348, 100360, 100362, 637334, 4124588, 10553439, 10553442, 10553455, 10553478, 10553505, 10553512, 10553827, 10553849, 69709712, 69709719, 69709728, 69709958, 21338685404 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..36.

Manfred Scheucher, Sage Script

MATHEMATICA

Select[Range[650000], Mod[Prime[#+1]-7, #]==0&] (* Harvey P. Dale, Sep 23 2021 *)

PROG

(Python)

def A105421(max) :

....terms = []

....p = 3

....for n in range(1, max+1) :

........if (p - 7) % n == 0 : terms.append(n)

........p = next_prime(p)

....return terms

end # Eric M. Schmidt, Feb 05 2013

(PARI) isok(n) = Mod(prime(n + 1), n) == Mod(7, n); \\ Michel Marcus, Apr 05 2015

(PARI) n=0; forprime(p=3, , if(Mod(p, n++)==7, print1(n", "))) \\ Charles R Greathouse IV, Jul 23 2015

CROSSREFS

Cf. A105286, A105287, A105288, A105290, A105329.

Sequence in context: A214700 A100997 A128657 * A273063 A217353 A258194

Adjacent sequences:  A105418 A105419 A105420 * A105422 A105423 A105424

KEYWORD

nonn

AUTHOR

Zak Seidov, May 02 2005

EXTENSIONS

a(1)-a(4) inserted by Eric M. Schmidt, Feb 05 2013

a(19)-a(22) from Harvey P. Dale, Apr 05 2015

a(23)-a(35) from Manfred Scheucher, Jul 23 2015

a(36) from Charles R Greathouse IV, Jul 23 2015

STATUS

approved

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Last modified May 26 17:16 EDT 2022. Contains 354092 sequences. (Running on oeis4.)