The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A125747

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A125747

a(n) is the smallest positive integer such that (Sum_{t(k)|n, 1 <= k <= a(n)} t(k)) >= n, where t(k) is the k-th positive divisor of n.
(history; published version)

#21 by N. J. A. Sloane at Sat Mar 24 18:50:10 EDT 2018

STATUS

proposed

approved

#20 by Jon E. Schoenfield at Wed Mar 21 20:48:51 EDT 2018

STATUS

editing

proposed

#19 by Jon E. Schoenfield at Wed Mar 21 20:48:49 EDT 2018

NAME

a(n) is the smallest positive integer such that (sumSum_{t(k)|n, 1 <= k <= a(n)} t(k)) is >= n, where t(k) is the k-th positive divisor of n..

STATUS

proposed

editing

#18 by Antti Karttunen at Wed Mar 21 12:26:50 EDT 2018

STATUS

editing

proposed

#17 by Antti Karttunen at Wed Mar 21 12:26:36 EDT 2018

COMMENTS

a(n) = the least number of divisors of n, taken in incrasing increasing order starting from as 1, A020639(n), A292269(n), etc. needed so that their sum is >= n. - Antti Karttunen, Mar 21 2018

#16 by Michel Marcus at Wed Mar 21 12:12:25 EDT 2018

MATHEMATICA

f[n_] := Block[{k = 1, d = Divisors[n]}, While[Sum[d[[i]], {i, k}] < n, k++ ]; k]; Table[f[n], {n, 105}] (* _Ray Chandler_, Dec 06 2006 *)

STATUS

proposed

editing

Discussion

Wed Mar 21

12:12

Michel Marcus: typo: incrasing

#15 by Antti Karttunen at Wed Mar 21 12:06:05 EDT 2018

STATUS

editing

proposed

#14 by Antti Karttunen at Wed Mar 21 11:32:59 EDT 2018

COMMENTS

a(n) = the least number of terms needed for a partial sum of divisors of n, when summed taken in the increasing incrasing order starting from 1 and not skipping any divisor, for which this , A020639(n), A292269(n), etc. needed so that their sum is >= n. - Antti Karttunen, Mar 21 2018

a(n) = the least number of divisors of n, taken in incrasing order starting from 1, A020639(n), etc. needed so that their sum is >= n. - Antti Karttunen, Mar 21 2018

CROSSREFS

Cf. A020639, A292269, A125746, A117553.

#13 by Antti Karttunen at Wed Mar 21 11:31:11 EDT 2018

COMMENTS

a(n) = the least number of divisors of n, taken in incrasing order starting from 1, A020639(n), etc. needed so that their sum is >= n. - Antti Karttunen, Mar 21 2018

#12 by Antti Karttunen at Wed Mar 21 11:27:45 EDT 2018

COMMENTS

a(n) = the least number of terms in needed for a partial sum of divisors of n (, when summed in the increasing order starting from 1) and not skipping any divisor, for which the this sum is >= n. - Antti Karttunen, Mar 21 2018