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A074792
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Least k>1 such that k^n == 1 (mod n).
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5
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2, 3, 4, 3, 6, 5, 8, 3, 4, 9, 12, 5, 14, 13, 16, 3, 18, 5, 20, 3, 4, 21, 24, 5, 6, 25, 4, 13, 30, 11, 32, 3, 34, 33, 36, 5, 38, 37, 16, 3, 42, 5, 44, 21, 16, 45, 48, 5, 8, 9, 52, 5, 54, 5, 16, 13, 7, 57, 60, 7, 62, 61, 4, 3, 66, 23, 68, 13, 70, 29, 72, 5, 74, 73, 16, 37, 78, 17, 80, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| If p is prime a(p)=p+1and a(2p)=2p-1; if n is in A050384 a(n)=n+1; if n is in A067945 a(n)=3 etc. It seems that sum(k=1, n, a(k)) is asymptotic to c*n^2 with c=0.2...
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MATHEMATICA
| Do[k = 2; While[ !IntegerQ[(k^n - 1)/n], k++ ]; Print[k], {n, 1, 80}] (from Robert G. Wilson v)
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PROG
| (PARI) a(n)=if(n<0, 0, s=2; while((s^n-1)%n>0, s++); s)
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CROSSREFS
| a(n) = {A076944(n)}^(1/n).
Cf. A076942, A076943, A076944.
Sequence in context: A126214 A126801 A076945 * A048276 A127463 A076618
Adjacent sequences: A074789 A074790 A074791 * A074793 A074794 A074795
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 07 2002
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