|
Search: id:A096526
|
|
|
| A096526 |
|
Initial values for f(x)=phi(sigma(x)) such that iteration of f ends in cycle of length=4. |
|
+0
10
|
|
| 324, 400, 484, 490, 530, 544, 576, 630, 660, 672, 684, 690, 714, 722, 750, 756, 768, 770, 772, 777, 780, 792, 804, 810, 819, 828, 832, 833, 840, 841, 846, 852, 858, 864, 868, 870, 872, 876, 888, 892, 901, 906, 910, 918, 920, 924, 930, 936, 940, 948, 952
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
EXAMPLE
|
n=324: trajectory=324, 660, [576, 1512, 1280, 864], 576, ...}
|
|
MATHEMATICA
|
g[n_] := EulerPhi[ DivisorSigma[1, n]]; f[n_] := f[n] = Block[{lst = NestWhileList[g, n, UnsameQ, All ]}, -Subtract @@ Flatten[ Position[lst, lst[[ -1]]]]]; Select[ Range[1000], f[ # ] == 4 &] (from Robert G. Wilson v Jul 14 2004)
|
|
CROSSREFS
|
Cf. A000010, A000203, A095952, A096887, A095953, A095954, A096888, A096889, A096890, A095955, A095956.
Sequence in context: A088214 A117550 A045287 this_sequence A111278 A014792 A064197
Adjacent sequences: A096523 A096524 A096525 this_sequence A096527 A096528 A096529
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Jul 13 2004
|
|
|
Search completed in 0.002 seconds
|
