This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
Table[k = 1; While[Mod[k!, n^n] > 0, k++ ]; k!/n^n, {n, 1, 10}] (* Stefan Steinerberger, Mar 11 2006 *)
a(10)=4 because 4 is the least positive integer that is not a sum of distinct divisors (namely 1,2,5 and 10) of 10.
a030057 n = head $ filter ((== 0) . p (a027750_row n)) [1..] where p _ 0 = 1 p [] _ = 0 p (k:ks) x = if x < k then 0 else p ks (x - k) + p ks x -- Reinhard Zumkeller, Feb 27 2012
with(combinat): with(numtheory): for n from 1 to 100 do div:=powerset(divisors(n)): b[n]:=sort({seq(sum(div[i][j],j=1..nops(div[i])),i=1..nops(div))}) od: for n from 1 to 100 do B[n]:={seq(k,k=0..1+sigma(n))} minus b[n] od: seq(B[n][1],n=1..100); # Emeric Deutsch, Aug 07 2005
a[n_] := First[ Complement[ Range[ DivisorSigma[1, n] + 1], Total /@ Subsets[ Divisors[n]]]]; Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Jan 02 2012 *)
from sympy import divisors def A030057(n): c = {0} for d in divisors(n,generator=True): c |= {a+d for a in c} k = 1 while k in c: k += 1 return k # Chai Wah Wu, Jul 05 2023
a(12): least positive k such that 144 divides k! is k=6, 6!=720. So a(12)=6.
Module[{nn=200,f},f=Range[nn]!;Position[f,#]&/@Table[SelectFirst[ f, Divisible[ #,n^2]&],{n,nn}]]//Flatten (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 11 2018 *)
TOP = 77
ii = [0]*TOP
for i in range(1, TOP):
ii[i] = i*i
f = k = y = 1
res = [-1]*TOP
while y
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