A054004 - OEIS

%I #33 Oct 27 2023 22:00:45

%S 14,1334,1634,2685,33998,42818,64665,84134,109214,122073,166934,

%T 289454,383594,440013,544334,605985,649154,655005,792855,1642154,

%U 2284814,2305557,2913105,3571905,3682622,4701537,5181045,6431732

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

%H Amiram Eldar, <a href="/A054004/b054004.txt">Table of n, a(n) for n = 1..1831</a> (calculated using the b-file at A002961; terms 1..967 from T. D. Noe)

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

%t Select[Range[100000], DivisorSigma[0, #] == DivisorSigma[0, # + 1] && DivisorSigma[1, #] == DivisorSigma[1, # + 1] &] (* _Jayanta Basu_, Mar 20 2013 *)

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

%K nonn

%O 1,1

%A _Asher Auel_, Jan 12 2000

%E More terms from _Jud McCranie_, Jun 02 2000