login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A333633 Smallest m such that sigma(m) == 2*n (mod phi(m)) or 0 if no solution exists. 1
1, 5, 24, 22, 21, 40, 48, 136, 110, 90, 88, 656, 102, 80, 96, 68, 55, 464, 65, 117, 91, 116, 85, 272, 95, 148, 133, 164, 115, 160, 147, 333, 247, 212, 145, 243968, 155, 244, 217, 405, 230, 11072, 185, 292, 259, 1184, 205, 237824, 215, 657, 301, 356, 189, 343, 329, 388, 559, 404 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(221) <= 288230257234804736 = 2^(k-2)*(2^k-443) for k=30. - Michel Marcus, Apr 02 2020

a(221) > 10^13. - Giovanni Resta, Apr 12 2020

LINKS

Michel Marcus, Table of n, a(n) for n = 0..220

PROG

(PARI) g(n) = my(f=factor(n)); sigma(f) % eulerphi(f);

a(n) = {n *= 2; my(k=1); while (g(k) != n, k++); k; } \\ Michel Marcus, Mar 30 2020

CROSSREFS

Bisection of A072808.

Cf. A000203, A000010, A063514, A067192, A067193.

Sequence in context: A200822 A112613 A305057 * A222355 A335352 A056234

Adjacent sequences:  A333630 A333631 A333632 * A333634 A333635 A333636

KEYWORD

nonn

AUTHOR

Michel Marcus, Mar 30 2020

EXTENSIONS

a(0) prepended by Jinyuan Wang, Mar 30 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 11 03:41 EDT 2022. Contains 356046 sequences. (Running on oeis4.)