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A248694 Odd numbers k such that the product of factorials of proper divisors of k does not divide k! 2
1575, 2835, 3465, 4095, 4725, 5355, 5775, 5985, 6435, 6615, 6825, 7245, 7875, 8085, 8505, 9135, 9765, 10395, 11025, 11655, 12285, 12705, 12915, 13545, 14175, 14805, 15015, 15435, 16065, 16695, 17325, 17955, 18585, 19215, 19305, 19635, 19845, 20475, 21105 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Is every term a multiple of 15?

LINKS

Table of n, a(n) for n=1..39.

EXAMPLE

Let Q(n) = n!/(product of the proper divisors of n).  Then Q(a(1)) = N/D, where

N = 5684447784292091153753490743683678065401858735042447947039489051000812450375

96097513516069953368913418355291373745171485235214678313832004750769512243570213

17329337171352254034549578081676132223379527381310854584384222707565139611863694

30640235947065824459529570708496537565356400158201705547084883398448628433876851

45027005261482010735089664203432206284363981438356549492398792517845833981953470

11656242198592638046634626564224371702079154967385329347508423182940832991802020

79729029554388862293013132314260080936743113826499242289158506713167932372780456

35478273889560173970236977657583276028820238215910913046229649347260976100815721

30514647760639026540100704923229175316918713642498606000080175020651282466288262

98949351261557660288695788306642653729696037113284350082653527072196917361726113

54899425631403773739526421814643000628257393623101868506322157155784868034570876

94944795541518746296597484128788416505102809202721810698024533196028905603665016

69160279455786632925907732365477717222525851009413148227878461914230042744382703

86503762563952079367594382974183048359869258795095100225724624706161418465202017

63929456631534509078212894380900186189087478989553793461391475049200947755236771

281068356116704064311250402286679067

and

D = 6449725440000.

MATHEMATICA

d[n_] := Drop[Divisors[n], -1]!; p[n_] := Apply[Times, d[n]]

u = Select[Range[25000], ! IntegerQ[#!/p[#]] &]; (* A248693 *)

Select[u, OddQ[#] &]  (* A248694 *)

CROSSREFS

Cf. A248692, A027750.

Sequence in context: A202465 A045291 A125014 * A075460 A203087 A278559

Adjacent sequences:  A248691 A248692 A248693 * A248695 A248696 A248697

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Oct 12 2014

STATUS

approved

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Last modified April 10 02:39 EDT 2020. Contains 333392 sequences. (Running on oeis4.)