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

Author

Amiram Eldar, Sep 20 2021

Keywords

• nonn

Examples

			2282175 is a term since A187795(2282175) = 4801650 > 2*2282175 = 4564350 and A187795(2282176) = 4630080 > 2*2282176 = 4564352.
		

Links

• David A. Corneth, Table of n, a(n) for n = 1..2372 (first 103 terms from Amiram Eldar)

Crossrefs

Subsequence of A005101, A096399 and A347935.

Cf. A187795, A347936, A347939.

Programs

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

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