A348698 Integers m such that sigma(m) + sigma(m+1) + sigma(m+2) - sigma(m+3) <= 0, where sigma is the sum of divisors.

10077, 15117, 20157, 25197, 27717, 37797, 41577, 42837, 45357, 50397, 55437, 65517, 69297, 70557, 75597, 81897, 83157, 85677, 90717, 92397, 98277, 100797, 102957, 105837, 110877, 120117, 120957, 124737, 125997, 128517, 131037, 136077, 138597, 142797, 147417, 147837

Offset: 1

Author

Michel Marcus, Oct 30 2021

Keywords

• nonn

Comments

Integers m such that A348688(m) <= 0.

At this time, only 2 integers are known with A348688(x)=0: 591357 and 735205677.

The least term not == 7 (mod 10) is 3027021.

Links

• Michel Marcus, Table of n, a(n) for n = 1..3269

Crossrefs

Cf. A000203, A348688.

Programs

Mathematica

s = DivisorSigma[1, Range[1.5*10^5]]; Position[s[[1 ;; -4]] + s[[2 ;; -3]] + s[[3 ;; -2]] - s[[4 ;; -1]], ?(# <= 0 &)] // Flatten (* _Amiram Eldar, Oct 30 2021 *)

PARI

isok(m) = sigma(m) + sigma(m+1) + sigma(m+2) - sigma(m+3) <= 0;