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 A334022 Numbers k such that s(k) = s(k+1) = s(k+2) = s(k+3), where s(k) is the sum of unitary divisors of k that are smaller than sqrt(k) (A334019). 0
 2, 46351754, 102841142, 158071592, 667930085, 851043553, 1097409992, 1580045430, 1595193655, 1698842487, 1919035496, 1951958341, 2279249234, 2507918727, 2520080695, 2741951910, 3335769314, 3654512455, 3713106152, 4209598844, 4351540982, 4369408604, 4480814965 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..23. EXAMPLE 2 is a term since A334019(2) = A334019(3) = A334019(4) = 1. MATHEMATICA s[n_] := DivisorSum[n, # &, #^2 < n && CoprimeQ[#, n/#] &]; seq={}; s1 = s[1]; s2 = s[2]; s3 = s[3]; Do[s4 = s[n]; If[s1 == s2 && s2 == s3 && s3 == s4, AppendTo[seq, n - 3]]; s1 = s2; s2 = s3; s3 = s4, {n, 4, 10^9}]; seq CROSSREFS Cf. A325175, A334019, A334020, A334021. Sequence in context: A247214 A367833 A135235 * A263645 A367834 A170998 Adjacent sequences: A334019 A334020 A334021 * A334023 A334024 A334025 KEYWORD nonn AUTHOR Amiram Eldar, Apr 12 2020 STATUS approved

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Last modified July 22 15:50 EDT 2024. Contains 374540 sequences. (Running on oeis4.)