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A045924 Numbers n such that prime(n) == -1 (mod n). 21
1, 2, 3, 4, 10, 70, 72, 182, 440, 1053, 6458, 6461, 6471, 40087, 40089, 251737, 251742, 637320, 637334, 637336, 1617173, 4124466, 10553445, 10553455, 10553569, 10553570, 10553574, 10553576, 10553819, 10553829, 27067100, 27067262, 69709705, 69709719, 69709734, 69709873 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Same as n such that n divides A008864(n). - David James Sycamore, Jul 23 2018

Also numbers n such that prime(n) == n-1 (mod n). - Muniru A Asiru, Jul 24 2018

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..108

E. Labos, Graph of prime(n) mod n

EXAMPLE

10 is a member because the 10th prime, 29, is congruent to -1 mod 10.

MATHEMATICA

NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; p = 1; Do[ If[Mod[p = NextPrim[p], n] == n - 1, Print[n]], {n, 1, 10^9}] (* Robert G. Wilson v, Feb 18 2004 *)

PROG

(PARI) isok(n) = Mod(prime(n), n) == -1; \\ Michel Marcus, Jul 24 2018

CROSSREFS

Cf. A004648 and esp. A023143.

Cf. A052013, A048891, A092044, A092045, A092046, A092047, A092048, A092049, A092050, A092051, A092052, A008864.

Sequence in context: A247204 A270375 A049204 * A244551 A068910 A146027

Adjacent sequences:  A045921 A045922 A045923 * A045925 A045926 A045927

KEYWORD

nonn

AUTHOR

Len Smiley

EXTENSIONS

More terms from Patrick De Geest, Nov 15 1999

Terms a(33) and beyond from Giovanni Resta, Feb 23 2020

STATUS

approved

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Last modified March 30 09:49 EDT 2020. Contains 333125 sequences. (Running on oeis4.)