The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A308480

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A308480

a(n) = A000225(n) if n is prime, a(n) = A020639(n) otherwise.
(history; published version)

#15 by N. J. A. Sloane at Thu Jul 18 07:45:50 EDT 2019

STATUS

proposed

approved

#14 by Felix Fröhlich at Sun Jun 23 14:37:08 EDT 2019

STATUS

editing

proposed

#13 by Felix Fröhlich at Sun Jun 23 14:35:01 EDT 2019

COMMENTS

For example, the trajectory of 11 under the above map starts 11, 2047, 23, 8388607, 47, 140737488355327, 2351, s, 4703, t, ..., where s is a 708-digit number and t is a 1416-digit number. t has no prime factor less than 2^64 (cf. GIMPS link).

LINKS

GIMPS, <a href="https://www.mersenne.org/report_exponent/?exp_lo=4703&exp_hi=&full=1">PrimeNet Exponent Status for M4703</a>

#12 by Felix Fröhlich at Sun Jun 23 14:26:37 EDT 2019

COMMENTS

For example, the trajectory of 11 under the above map starts 11, 2047, 23, 8388607, 47, 140737488355327, 2351, s, 4703, t, ..., where s is a 708-digits digit number and t is a 1416-digit number.

#11 by Felix Fröhlich at Sun Jun 23 14:18:44 EDT 2019

COMMENTS

For example, the trajectory of 11 under the above map starts 11, 2047, 23, 8388607, 47, 140737488355327, 2351, k, s, 4703, t, ..., where k is a number with s 708 -digits number and t is a 1416-digit number.

#10 by Felix Fröhlich at Sun Jun 23 14:10:27 EDT 2019

COMMENTS

For example, the trajectory of 11 under the above map starts 11, 2047, 23, 8388607, 47, 140737488355327, 2351, k, 4703, ..., where k is a number with 708 digits.

STATUS

proposed

editing

#9 by Jon E. Schoenfield at Fri May 31 00:23:23 EDT 2019

STATUS

editing

proposed

#8 by Jon E. Schoenfield at Fri May 31 00:23:17 EDT 2019

COMMENTS

For example, the trajectory of 11 under the above map starts 11, 2047, 23, 8388607, 47, 140737488355327, 2351, k, ...., , where k is a number with 708 digits.

STATUS

proposed

editing

#7 by Felix Fröhlich at Thu May 30 04:55:52 EDT 2019

STATUS

editing

proposed

Discussion

Thu May 30

05:04

Felix Fröhlich: Initially I planned to submit a square array of the trajectories of the starting values n. But the values of that array got large quickly, so I decided to submit this sequence instead and mention the problem that originally lead me to it in a comment.

#6 by Felix Fröhlich at Thu May 30 04:54:42 EDT 2019

COMMENTS

For example, the trajectory of 11 under the above map starts 11, 2047, 23, 8388607, 47, 140737488355327, 2351, p, k, ...., where p k is a number with 708 digits.