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A066708
Least m such that n = m mod tau(m) if such m exists, otherwise 0.
2
3, 6, 15, 28, 165, 30, 135, 48, 144, 192, 1755, 300, 1485, 270, 2079, 336, 6237, 1008, 9639, 1728, 1296, 3510, 28215, 1080, 16900, 2970, 10395, 7840, 12285, 4158, 41055, 4752, 40425, 12474, 48195, 3780, 220077, 19278, 51975, 10920, 356265, 9450
OFFSET
1,1
COMMENTS
By definition, a(n) >= n. If the condition is changed to n == m mod tau(m), then a(n) = 1 for all n. - Chai Wah Wu, Mar 14 2023
LINKS
MATHEMATICA
Module[{nn=500000, mtm}, mtm=Table[{m, Mod[m, DivisorSigma[0, m]]}, {m, nn}]; Table[ SelectFirst[mtm, #[[2]]==n&], {n, 50}]][[All, 1]] (* Harvey P. Dale, Jan 10 2023 *)
PROG
(Python)
from itertools import count
from sympy import divisor_count
def A066708(n): return next(filter(lambda m:m%divisor_count(m)==n, count(n))) # Chai Wah Wu, Mar 14 2023
CROSSREFS
Cf. A000005.
Sequence in context: A063834 A139117 A226736 * A034464 A116696 A000220
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Jan 14 2002
STATUS
approved