A347937 Numbers k such that k and k+1 are both terms of A347935.

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

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.

Cf. A187795, A347936, A347939.

Sequence in context: A089446 A204603 A176382 * A339937 A092017 A238079

Adjacent sequences: A347934 A347935 A347936 * A347938 A347939 A347940

Keyword

nonn

Author

Amiram Eldar, Sep 20 2021

Status

approved