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 A324255 Lesser of super amicable pair m < n defined by sigma(sigma(m)) = sigma(sigma(n)) = m + n. 1
 23, 14999, 34673, 55373, 2056961, 2458187, 4586987, 5174363, 6204767, 15788453, 20699927, 22239647, 25748273, 43428947, 53636627, 74005637, 92626307, 132253139, 134131379, 158486747, 167677187, 183614987, 307412933, 385042487, 413859143, 418168343, 683772017 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The larger numbers in each pair are in A324256. Analogous to A002025 as A019279 is analogous to A000396. LINKS EXAMPLE (23, 37) are the first pair since sigma(sigma(23)) = sigma(sigma(37)) = 60 = 23 + 37. MATHEMATICA seq={}; s[n_]:=DivisorSigma[1, DivisorSigma[1, n]]-n; Do[m=s[n]; If[m>n && s[m]==n, AppendTo[seq, n]], {n, 1, 60000}]; seq PROG (PARI) f(n) = sigma(sigma(n)) - n; lista(nn) = {for (n=1, nn, my(fn = f(n)); if ((fn > n) && (f(fn) == n), print1(n, ", ")); ); } \\ Michel Marcus, Feb 20 2019 CROSSREFS Cf. A000203, A000396, A002025, A019279, A045613 (unitary analog), A051027, A324256. Sequence in context: A090674 A013728 A028693 * A273940 A348307 A033998 Adjacent sequences:  A324252 A324253 A324254 * A324256 A324257 A324258 KEYWORD nonn AUTHOR Amiram Eldar, Feb 19 2019 STATUS approved

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Last modified December 3 20:35 EST 2021. Contains 349468 sequences. (Running on oeis4.)