A049051 Numbers k such that k through k+4 all have the same number of divisors.

11605, 12855, 13782, 19142, 21494, 28374, 28375, 40311, 42805, 50582, 55254, 60231, 60663, 79094, 87655, 90181, 90182, 95845, 99655, 103621, 109765, 115591, 120727, 121045, 122151, 122871, 142454, 142806, 152630, 157493, 157494, 171893

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Donovan Johnson)

Mathematica

Flatten[Position[Partition[DivisorSigma[0, Range[200000]], 5, 1], _?(Length[ Union[#]] == 1&), {1}, Heads->False]] (* Harvey P. Dale, May 30 2014 *)
SequencePosition[DivisorSigma[0, Range[200000]], {x_, x_, x_, x_, x_}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 03 2017 *)

Crossrefs

Cf. A000005, A006558, A019273, A039665, A119479.

Other runs of equidivisor numbers: A005237 (runs of 2), A005238 (runs of 3), A006601 (runs of 4), A049052 (runs of 6), A049053 (runs of 7).

Sequence in context: A226905 A162865 A237534 * A250242 A231321 A154053

Adjacent sequences: A049048 A049049 A049050 * A049052 A049053 A049054

Keyword

nonn,changed

Author

David W. Wilson

Status

approved