The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A216392 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A216392

Number of values of k for which sigma(k) is a permutation of decimal digits of k, for k < 2^n.
(history; published version)

#19 by Bruno Berselli at Sat Mar 29 03:27:49 EDT 2014

STATUS

proposed

approved

#18 by Joerg Arndt at Sat Mar 29 03:05:31 EDT 2014

STATUS

editing

proposed

#17 by Joerg Arndt at Sat Mar 29 03:05:26 EDT 2014

FORMULA

a(n) = # { k in A115920 | k < 2^n }. - M. F. Hasler, Feb 24 2014

PROG

(PARI) a(n)=sum(k=1, 2^n, vecsort(digits(k)) == vecsort(digits(sigma(k)))) \\ Use digits(n)=eval(Vec(Str(n))) in old versions of PARI. - __V. Raman_, Feb 18 2014, based on edits by M. F. Hasler

#16 by V. Raman at Thu Mar 06 05:54:44 EST 2014

FORMULA

a(n) = # { k in A115920 | k < 2^n }. - M. F. Hasler, Feb 24 2014

Discussion

Fri Mar 28

03:22

OEIS Server: This sequence has not been edited or commented on for a week
yet is not proposed for review.  If it is ready for review, please
visit https://oeis.org/draft/A216392 and click the button that reads
"These changes are ready for review by an OEIS Editor."

Thanks.
  - The OEIS Server

#15 by V. Raman at Thu Mar 06 03:05:42 EST 2014

PROG

(PARI) a(n)=sum(k=1, 2^n, vecsort(digits(k)) == vecsort(digits(sigma(k)))) \\ Use digits(n) = vectoreval(lengthVec(Str(n)), i, truncate(n/(10^(i-1)))%10) in old versions of PARI. - _V. Raman_, Feb 18 2014, based on edits by _M. F. Hasler_

a(n)=m=0; for(k=1, 2^n, if(vecsort(digits(k))==vecsort(digits(sigma(k))), m++)); m \\ V. Raman, Feb 18 2014

STATUS

approved

editing

Discussion

Thu Mar 06

03:41

V. Raman: Editor Hasler's edits to my program in A216393 looks good, (thanks for your input) and I have edited the remaining 11 in the same way. I am sorry I didn't do the edits immediately (which I could have done in a moment) because I didn't want to get into trouble exceeding my quota... May I suggest you always go easy with these quota restrictions - it looks meaningless to me and causes chain reaction of trouble. At least /editing queue could be free from these quota restrictions and always easy going.

Hope all goes well.

All is well.

There are some people who are helpful and showing good will from among OEIS editors.

Leaving all my drafts in /editing queue

03:52

V. Raman: I left a note in A216391 earlier

#14 by M. F. Hasler at Tue Feb 18 23:15:55 EST 2014

STATUS

proposed

approved

#13 by V. Raman at Tue Feb 18 11:01:03 EST 2014

STATUS

editing

proposed

#12 by V. Raman at Tue Feb 18 10:53:16 EST 2014

PROG

(PARI) digits(n) = vecsort(vector(length(Str(n)), i, truncate(n/(10^(i-1)))%10))

a(n)=m=0; for(k=1, 2^n, if(vecsort(digits(k))==vecsort(digits(sigma(k)), ), m++)); m \\ V. Raman, Feb 18 2014

STATUS

proposed

editing

#11 by V. Raman at Tue Feb 18 07:28:20 EST 2014

STATUS

editing

proposed

#10 by V. Raman at Tue Feb 18 07:26:00 EST 2014

EXAMPLE

a(10) = 7 because the values of k satisfying the condition for k < 2^10 are {1, 69, 258, 270, 276, 609, 639}. - _V. Raman, _, Feb 18 2014

PROG

(PARI) digits(n) = vecsort(vector(length(Str(n)), i, truncate(n/(10^(i-1)))%10))

STATUS

proposed

editing