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A325847 Lesser of exponentially-odd amicable numbers pair: numbers m < k such that m = s(k) and k = s(m), where s(k) is the sum of proper exponential-odd divisors of k. 2
366, 3864, 16104, 16536, 59808, 71904, 142290, 142310, 196248, 198990, 240312, 326424, 341088, 348840, 366792, 520608, 664608, 704352, 753312, 912072, 1077890, 1156870, 1184490, 1511930, 1669910, 1805490, 1863456, 1936776, 2195640, 2236570, 2517480, 2686440 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The sum of proper exponential-odd divisors of k is A033634(k) - k if k is exponentially odd (A268335), or A033634(k) if not.

The larger counterparts are in A325848.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..789 (terms below 10^10)

MATHEMATICA

f[e_] := If[OddQ[e], e + 2, e + 1]; fun[p_, e_] := 1 + (p^f[e] - p)/(p^2 - 1); a[1] = 1; a[n_] := Times @@ (fun @@@ (fct = FactorInteger[n])) - If[AllTrue[fct[[;; , 2]], OddQ], n, 0]; s = {}; Do[m = a[n]; If[m > n && a[m] == n, AppendTo[s, n]], {n, 1, 10^5}]; s

CROSSREFS

Cf. A033289, A033634, A268335, A325848.

Sequence in context: A033174 A249704 A260281 * A279982 A286793 A079493

Adjacent sequences:  A325844 A325845 A325846 * A325848 A325849 A325850

KEYWORD

nonn

AUTHOR

Amiram Eldar, Sep 07 2019

STATUS

approved

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Last modified April 5 13:26 EDT 2020. Contains 333241 sequences. (Running on oeis4.)