A045924 - OEIS

%I #33 Feb 23 2020 08:40:55

%S 1,2,3,4,10,70,72,182,440,1053,6458,6461,6471,40087,40089,251737,

%T 251742,637320,637334,637336,1617173,4124466,10553445,10553455,

%U 10553569,10553570,10553574,10553576,10553819,10553829,27067100,27067262,69709705,69709719,69709734,69709873

%N Numbers n such that prime(n) == -1 (mod n).

%C Same as n such that n divides A008864(n). - _David James Sycamore_, Jul 23 2018

%C Also numbers n such that prime(n) == n-1 (mod n). - _Muniru A Asiru_, Jul 24 2018

%H Giovanni Resta, <a href="/A045924/b045924.txt">Table of n, a(n) for n = 1..108</a>

%H E. Labos, <a href="/A004648/a004648.gif">Graph of prime(n) mod n</a>

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

%t 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 *)

%o (PARI) isok(n) = Mod(prime(n), n) == -1; \\ _Michel Marcus_, Jul 24 2018

%Y Cf. A004648 and esp. A023143.

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

%K nonn

%O 1,2

%A _Len Smiley_

%E More terms from _Patrick De Geest_, Nov 15 1999

%E Terms a(33) and beyond from _Giovanni Resta_, Feb 23 2020