|
Search: id:A058214
|
|
|
| A058214 |
|
Sum of solutions of phi(x)=2^n. |
|
+0
3
|
|
| 3, 13, 35, 105, 231, 581, 1315, 3225, 6711, 15221, 32755, 74505, 154407, 339397, 718115, 1589145, 3243831, 6946421, 14482675, 31259145, 63894567, 135588037, 281203235, 601400985, 1219907127, 2557715317, 5267017715, 11123540745
(list; graph; listen)
|
|
|
OFFSET
|
0,1
|
|
|
EXAMPLE
|
For n=6, 2^n=64; the solutions of phi(x)=64 are {85,128,136,160,170,192,204,240}, whose sum is a(6)=1315.
|
|
MATHEMATICA
|
phiinv[n_, pl_] := Module[{i, p, e, pe, val}, If[pl=={}, Return[If[n==1, {1}, {}]]]; val={}; p=Last[pl]; For[e=0; pe=1, e==0||Mod[n, (p-1)pe/p]==0, e++; pe*=p, val=Join[val, pe*phiinv[If[e==0, n, n*p/pe/(p-1)], Drop[pl, -1]]]]; Sort[val]]; phiinv[n_] := phiinv[n, Select[1+Divisors[n], PrimeQ]]; Table[Plus@@phiinv[2^n], {n, 0, 30}] (* phiinv[n, pl] = list of x with phi(x)=n and all prime divisors of x in list pl. phiinv[n] = list of x with phi(x)=n *)
|
|
CROSSREFS
|
Cf. A000010, A001317, A003401, A004729, A019434, A045544, A047999, A053576, A054432, A058213, A058215.
Sequence in context: A016061 A137976 A095661 this_sequence A108480 A061483 A128288
Adjacent sequences: A058211 A058212 A058213 this_sequence A058215 A058216 A058217
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Nov 30 2000
|
|
EXTENSIONS
|
Edited by Dean Hickerson (dean(AT)math.ucdavis.edu), Jan 25 2002
|
|
|
Search completed in 0.002 seconds
|
