A140578 A positive integer n is included if n is the smallest integer in a run of a plural number of consecutive integers all with the same number of divisors.

2, 14, 21, 26, 33, 38, 44, 57, 75, 85, 93, 98, 104, 116, 118, 122, 133, 135, 141, 145, 147, 158, 171, 177, 189, 201, 205, 213, 217, 230, 242, 253, 285, 296, 298, 301, 326, 332, 334, 344, 374, 381, 387, 393, 429, 434, 445, 453, 481, 501, 507, 514, 526, 537, 542

Offset: 1

Author

Leroy Quet, Jul 05 2008

Keywords

• nonn

Comments

All terms of this sequence are included in sequence A005237.

Examples

			d(33) = d(34) = d(35), where d(n) is the number of divisors of n. And since d(32) does not equal d(33), d(33) is the first term of this run of similar values. So 33 is included in this sequence.
		

Crossrefs

Cf. A005237.

Programs

Mathematica

(First /@ Select[ Split[ Table[ {DivisorSigma[0, n], n}, {n, 1, 600}], First[#1] == First[#2] &] , Length[#] > 1 &])[[All, 2]] (* Jean-François Alcover, Oct 07 2013 *)

Extensions

Extended by Ray Chandler, Jun 25 2009