A324310 Numbers k such that s(k) = s(k+1) = s(k+2) where s(k) is the sum of divisors of k that are smaller than sqrt(k) (A070039).

2, 3, 2505, 64486, 113413, 205365, 423414, 496156, 635053, 664033, 881565, 1011793, 1190685, 1306605, 1442136, 1923655, 1947766, 2286913, 2324422, 2465805, 3030733, 3291553, 3335205, 4100086, 4547353, 4648965, 4987065, 5025705, 5034904, 5069113, 5827485, 5909413

Offset: 1

Author

Amiram Eldar, Sep 03 2019

Keywords

• nonn

Comments

Are there 4 consecutive numbers with the same value of A070039, apart from 2, 3, 4, 5?

The next 4 consecutive numbers with the same value of A070039 start at 1190499411. - Giovanni Resta, Sep 05 2019

Examples

			2 is in the sequence since A070039(2) = A070039(3) = A070039(4) = 1.
		

Crossrefs

Cf. A070039, A324295, A325175.

Programs

Mathematica

s[n_] := DivisorSum[n, # &, # < Sqrt[n] &]; seq={}; s1 = 0; s2=0; Do[s3 = s[n]; If[s1 == s2 && s2 == s3, AppendTo[seq, n - 2]]; s1 = s2; s2 = s3, {n, 2, 10^5}]; seq