|
Search: id:A076495
|
|
|
| A076495 |
|
Smallest x such that Mod[sigma[x],x]=n, or 0 if no such x exists. |
|
+0
3
|
|
| 2, 20, 4, 9, 0, 25, 8, 10, 15, 14, 21, 24, 27, 22, 16, 26, 39, 208, 36, 34, 51, 38, 57, 112, 95, 46, 69, 48, 115, 841, 32, 58, 45, 62, 93, 660, 155, 1369, 162, 44, 63, 1681, 50, 82, 123, 52, 129, 60, 75, 94, 72, 352, 235, 90, 329, 84, 99, 68, 265, 96, 371, 118, 64, 76
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
The 0 entries are at present only conjectures.
|
|
EXAMPLE
|
n=1: solution=smallest prime. n=3: Mod[sigma[4],4]=Mod[7,4]=3=a(4), n=5: Very difficult case, no solution below 10^7.
|
|
MATHEMATICA
|
f[x_] := s=Mod[DivisorSigma[1, n], n]; t=Table[0, {256}]; Do[s=f[n]; If[s<257&&t[[s]]==0, t[[s]]=n], {n, 1, 10000000}]; t
|
|
CROSSREFS
|
Cf. A045768, A045769, A045770.
Sequence in context: A082259 A077339 A077341 this_sequence A058403 A083297 A012739
Adjacent sequences: A076492 A076493 A076494 this_sequence A076496 A076497 A076498
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Oct 21 2002
|
|
EXTENSIONS
|
The "more" keyword is because of the zero entries.
|
|
|
Search completed in 0.002 seconds
|
