A054004 Numbers k such that k and k+1 have the same number and sum of divisors.

14, 1334, 1634, 2685, 33998, 42818, 64665, 84134, 109214, 122073, 166934, 289454, 383594, 440013, 544334, 605985, 649154, 655005, 792855, 1642154, 2284814, 2305557, 2913105, 3571905, 3682622, 4701537, 5181045, 6431732

Offset: 1

Author

Asher Auel, Jan 12 2000

Keywords

• nonn

Examples

			Divisors of 14 = {1, 2, 7, 14}, divisors of 15 = {1, 3, 5, 15}, both have four divisors and sum = 24.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1831 (calculated using the b-file at A002961; terms 1..967 from T. D. Noe)

Crossrefs

Cf. A000005, A000203, A002961, A005237, A053249, A054005, A054006, A054007.

Programs

Mathematica

Select[Range[100000], DivisorSigma[0, #] == DivisorSigma[0, # + 1] && DivisorSigma[1, #] == DivisorSigma[1, # + 1] &] (* Jayanta Basu, Mar 20 2013 *)

Extensions

More terms from Jud McCranie, Jun 02 2000