A055006 - OEIS

A055006

a(n) is the least multiple of n such that a(n) = 1 mod k for all integers k with 1 < k < n and k relatively prime to n.

1, 2, 3, 4, 25, 6, 301, 736, 2241, 190, 25201, 4236, 83161, 19306, 64065, 135136, 7207201, 85086, 49008961, 49468420, 36951201, 27776386, 698377681, 855189336, 25700298625, 2445441076, 74364290001, 13624600276, 2248776129601, 6254036790, 39594522567601

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..31.

MATHEMATICA

Table[Block[{m = 1, t = Select[Range[2, n - 1], CoprimeQ[#, n] &]}, While[! AllTrue[t, Mod[m n, #] == 1 &], m++]; m n], {n, 20}] (* Michael De Vlieger, Mar 08 2022 *)

PROG

(PARI) isok(m, n) = for (k=2, n-1, if ((gcd(k, n)==1) && ((m % k) !=1), return(0))); return(1);

a(n) = my(m=n); while (!isok(m, n), m+=n); m; \\ Michel Marcus, Mar 08 2022

CROSSREFS

Sequence in context: A287433 A235041 A080613 * A139050 A043309 A104386

Adjacent sequences: A055003 A055004 A055005 * A055007 A055008 A055009

KEYWORD

nonn

AUTHOR

Stephen G Penrice, May 30 2000

EXTENSIONS

More terms from Sean A. Irvine, Mar 07 2022

STATUS

approved