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A045924 Numbers n such that prime(n) == -1 (mod n). 20
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 (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

Table of n, a(n) for n=1..32.

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

STATUS

approved

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Last modified November 14 07:19 EST 2019. Contains 329111 sequences. (Running on oeis4.)