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A057921 d(n+1) divides d(n), where d(n) is number of positive divisors of n. 4

%I

%S 2,6,10,12,14,18,21,22,26,28,30,33,34,38,40,42,44,46,52,54,56,57,58,

%T 60,66,70,72,75,78,80,82,84,85,86,88,90,93,94,96,98,102,104,105,106,

%U 108,110,112,114,116,118,122,126,128,130,132,133,135,136,138,140,141,142

%N d(n+1) divides d(n), where d(n) is number of positive divisors of n.

%H Ivan Neretin, <a href="/A057921/b057921.txt">Table of n, a(n) for n = 0..10000</a>

%e 10 is included because d(11) = 2 divides d(10) = 4.

%t Select[Range@150, Divisible @@ DivisorSigma[0, {#, # + 1}] &] (* _Ivan Neretin_, May 29 2015 *)

%Y Cf. A057922, A005237.

%K nonn

%O 0,1

%A _Leroy Quet_, Nov 11 2000

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Last modified May 18 08:30 EDT 2022. Contains 353785 sequences. (Running on oeis4.)