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A019530
Smallest number m such that m^m is divisible by n.
3
0, 2, 3, 2, 5, 6, 7, 4, 3, 10, 11, 6, 13, 14, 15, 4, 17, 6, 19, 10, 21, 22, 23, 6, 5, 26, 3, 14, 29, 30, 31, 4, 33, 34, 35, 6, 37, 38, 39, 10, 41, 42, 43, 22, 15, 46, 47, 6, 7, 10, 51, 26, 53, 6, 55, 14, 57, 58, 59, 30, 61, 62, 21, 4, 65, 66, 67, 34, 69, 70, 71, 6, 73, 74, 15, 38, 77, 78
OFFSET
1,2
COMMENTS
Numbers n such that a(n) = n are 2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 26, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 46, 47, 51, 53, 55, 57, 58, 59, 61, 62, 65, 66, 67, 69, 70, ... (A144338). - Altug Alkan, Sep 30 2016
For n > 1, a(n) = A007947(n) * k for some k. Mostly, k = 1. - David A. Corneth, Sep 30 2016
For n > 1, a(n) = A007947(n) if and only if A007947(n) >= A051903(n). - Robert Israel, Sep 30 2016
MATHEMATICA
a[1] = 0; a[n_] := For[m = 2, True, m++, If[PowerMod[m, m, n] == 0, Return[m]]]; Array[a, 100] (* Jean-François Alcover, Sep 30 2016 *)
PROG
(PARI) a(n)={my(f=factor(n)[, 1], p=prod(i=1, #f, f[i]), i=1); if(n==1, return(0)); while(1, if(Mod(p*i, n)^(p*i)==0, return(p*i) , i++))} \\ David A. Corneth, Sep 30 2016
(PARI) a(n)=if(n<=1, return(0)); for(m=2, n, if(Mod(m, n)^m==0, return(m))); \\ Joerg Arndt, Oct 01 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
D. Muller (Research37(AT)aol.com)
STATUS
approved

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Last modified September 22 07:30 EDT 2024. Contains 376097 sequences. (Running on oeis4.)