A349871 a(n) is the start of the least run of exactly n consecutive nobly abundant numbers (A349758).

60, 735, 1274, 28674, 19940, 1699947, 4630544, 24816974, 111500620, 262315467, 30477326444

Offset

1,1

Comments

a(12) > 1.6*10^11, if it exists.

Links

Table of n, a(n) for n=1..11.

Example

a(2) = 735 since 735 and 736 are the least pair of consecutive numbers that are nobly abundant numbers.

Mathematica

abQ[n_] := DivisorSigma[1, n] > 2*n; nobAbQ[n_] := And @@ abQ /@ DivisorSigma[{0, 1}, n]; seq[len_, nmax_] := Module[{s = Table[0, {len}], count = 0, n = 1, n1, d}, While[n < nmax && count < len, n1 = n; If[nobAbQ[n], While[nobAbQ[++n1]]; d = n1 - n; If[d <= len && s[[d]] == 0, count++; s[[d]] = n]]; n = n1 + 1]; TakeWhile[s, # > 0 &]]; seq[6, 10^6]

Crossrefs

Cf. A349758, A349870.

Sequence in context: A138409 A024016 A348583 * A112042 A168307 A323566

Adjacent sequences: A349868 A349869 A349870 * A349872 A349873 A349874

Keyword

nonn,more

Author

Amiram Eldar, Dec 03 2021

Status

approved