OFFSET
1,2
COMMENTS
k is a multiple of n.
A search limit of 2*n^2 (as suggested by Hugo Pfoertner on the SeqFan list) appears to be sufficient: Up to n = 10^5, the largest ratio r(n) = a(n)/n is r(90090) = 672. - M. F. Hasler, Apr 04 2022
It appears that even a(n) <= 16*n^(4/3), verified up to n = 10^6 with search limit 2*n^2. Large values of a(n)/n^(4/3) are reached in particular at multiples of 2*3*5*7*11, but also at 2^3*3^3*5*11*13. See A352834 for more. - M. F. Hasler, Apr 15 2022
LINKS
M. F. Hasler, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = n*A352834(n). - M. F. Hasler, Apr 15 2022
MATHEMATICA
a = Table[0, {100}]; Do[b = Denominator[DivisorSigma[0, n]/n]; If[b < 101 && a[[b]] == 0, a[[b]] = n], {n, 1, 2640}]; a
PROG
(PARI) apply( {A091895(n, L=n^2*2)=forstep(k=n, L, n, denominator(numdiv(k)/k)==n&&return(k))}, [1..99]) \\ M. F. Hasler, Apr 04 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Feb 09 2004
STATUS
approved