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A049051 Numbers n such that n through n+4 all have same number of divisors. 10
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..1000

MAPLE

with(numtheory); A049051:=proc(q, w) local k, ok, n;

for n from 1 to q do ok:=1;

for k from 1 to w do if tau(n)<>tau(n+k) then ok:=0; break; fi; od;

if ok=1 then print(n); fi; od; end: A049051(10^6, 4); # Paolo P. Lava, May 03 2013

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, A005237, A005238, A006601, A006558, A019273, A039665, A049052, A049053.

Sequence in context: A226905 A162865 A237534 * A250242 A231321 A154053

Adjacent sequences:  A049048 A049049 A049050 * A049052 A049053 A049054

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified February 20 01:06 EST 2018. Contains 299357 sequences. (Running on oeis4.)