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A353901
Numbers k such that A353900(k) is divisible by k.
0
1, 6, 28, 56, 1104, 2208, 2178540, 4357080, 6499584, 12999168
OFFSET
1,2
COMMENTS
a(11) > 8*10^10, if it exists.
The corresponding ratios A353900(k)/k are 1, 2, 2, 1, 2, 1, 4, 2, 2, 1, ...
EXAMPLE
6 is a term since A353900(6) = 12 is divisible by 6.
56 is a term since A353900(56) = 56 is divisible by 56.
MATHEMATICA
f[p_, e_] := 1 + Sum[p^(2^k), {k, 0, Floor[Log2[e]]}]; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[6.5*10^6], Divisible[s[#], #] &]
CROSSREFS
Cf. A353900.
Similar sequences: A007691, A189000, A327158, A348601.
Sequence in context: A254879 A298168 A317478 * A081537 A058007 A033588
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, May 10 2022
STATUS
approved