This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A322542 Larger of semi-unitary amicable numbers pair: numbers (m, n) such that susigma(m) = susigma(n) = m + n, where susigma(n) is the sum of the semi-unitary divisors of n (A322485). 2
 126, 378, 1260, 3780, 4584, 5544, 11424, 15390, 16632, 16728, 25296, 49308, 68760, 73962, 88608, 84336, 179118, 168730, 172560, 225096, 256338, 266568, 250920, 297024, 287280, 365700, 374304, 391656, 374418, 387720, 386568, 393528, 548550, 502656, 623280 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The terms are ordered according to the order of their lesser counterparts (A322541). LINKS EXAMPLE 126 is in the sequence since it is the larger of the amicable pair (114, 126): susigma(114) = susigma(126) = 114 + 126. MATHEMATICA f[p_, e_] := (p^Floor[(e + 1)/2] - 1)/(p - 1) + p^e; s[n_] := If[n == 1, 1, Times @@ (f @@@ FactorInteger[n])] - n; seq = {}; Do[n = s[m]; If[n > m && s[n] == m, AppendTo[seq, n]], {m, 1, 1000000}]; seq PROG (PARI) susigma(n) = {my(f = factor(n)); for (k=1, #f~, my(p=f[k, 1], e=f[k, 2]); f[k, 1] = (p^((e+1)\2) - 1)/(p-1) + p^e; f[k, 2] = 1; ); factorback(f); } \\ A322485 lista(nn) = {for (n=1, nn, my(m=susigma(n)-n); if ((m > n) && (susigma(m) == n + m), print1(m, ", ")); ); } \\ Michel Marcus, Dec 15 2018 CROSSREFS Cf. A002025, A002952, A322485, A322486, A322541. Sequence in context: A063334 A181262 A181255 * A323759 A102805 A267556 Adjacent sequences:  A322539 A322540 A322541 * A322543 A322544 A322545 KEYWORD nonn AUTHOR Amiram Eldar, Dec 14 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 25 17:47 EDT 2019. Contains 324353 sequences. (Running on oeis4.)