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A347937 Numbers k such that k and k+1 are both terms of A347935. 1
2282175, 16769024, 18356624, 27252224, 32493824, 35820224, 46577024, 50968575, 51962624, 53992575, 55130624, 61854975, 63101024, 63140175, 69980624, 72525375, 73378304, 74376224, 80791424, 82389824, 98834175, 102650624, 105674624, 107769375, 109001024, 110238975 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
David A. Corneth, Table of n, a(n) for n = 1..2372 (first 103 terms from Amiram Eldar)
EXAMPLE
2282175 is a term since A187795(2282175) = 4801650 > 2*2282175 = 4564350 and A187795(2282176) = 4630080 > 2*2282176 = 4564352.
MATHEMATICA
abQ[n_] := DivisorSigma[1, n] > 2*n; s[n_] := DivisorSum[n, # &, abQ[#] &]; q[n_] := s[n] > 2*n; seq = {}; q1 = q[1]; Do[q2 = q[n]; If[q1 && q2, AppendTo[seq, n-1]]; q1 = q2, {n, 2, 2*10^7}]; seq
PROG
(PARI) isok1(k) = sumdiv(k, d, if (sigma(d)>2*d, d)) > 2*k; \\ A347935
isok(k) = isok1(k) && isok1(k+1); \\ Michel Marcus, Sep 20 2021
CROSSREFS
Subsequence of A005101, A096399 and A347935.
Sequence in context: A089446 A204603 A176382 * A339937 A092017 A238079
KEYWORD
nonn
AUTHOR
Amiram Eldar, Sep 20 2021
STATUS
approved

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Last modified May 24 05:24 EDT 2024. Contains 372772 sequences. (Running on oeis4.)