A097016 a(n)=x is the first term in chain of consecutive integers, for all of which the value of sigma[x] is divisible by 6.

5, 5, 22, 44, 85, 85, 230, 260, 352, 950, 950, 1172, 1172, 1172, 1172, 1172, 1172, 1172, 1172, 1901, 1901, 7249, 7249, 7249, 12932, 12932, 12932, 12932, 12932, 38852, 38852, 226324, 226324, 235372, 235372, 235372, 413974, 413974, 423485, 423485

Offset

1,1

Comments

It appears that arbitrarily long chains exist.

Links

Table of n, a(n) for n=1..40.

Example

n=52: a(52)=1270685 means that all entries in {sigma[a(52)],...,sigma[1270685+52-1]} ={1666224,...,2520672} are divisible by 6.

Mathematica

With[{ds=Table[If[Divisible[DivisorSigma[1, n], 6], 1, 0], {n, 450000}]}, Flatten[ Table[SequencePosition[ds, PadRight[{}, n, 1], 1], {n, 40}], 1][[All, 1]]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 06 2018 *)

Crossrefs

Cf. A000203, A084301, A074627.

Sequence in context: A365104 A014619 A205140 * A183257 A255456 A338936

Adjacent sequences: A097013 A097014 A097015 * A097017 A097018 A097019

Keyword

nonn

Author

Labos Elemer, Aug 23 2004

Status

approved