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A074202 Numbers k such that the number of 1's in the binary expansion of k divides 2^k-1. 3

%I #21 Mar 09 2023 16:52:46

%S 1,2,4,8,14,16,22,26,28,32,38,42,44,50,52,56,64,70,74,76,82,84,88,98,

%T 100,104,112,124,128,134,138,140,146,148,152,162,164,168,176,188,194,

%U 196,200,208,220,224,236,244,248,256,262,266,268,274,276,280,290,292

%N Numbers k such that the number of 1's in the binary expansion of k divides 2^k-1.

%C Odd terms (1, 351, 375, ...) are in A074203.

%H Amiram Eldar, <a href="/A074202/b074202.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[300], (d = DigitCount[#, 2, 1]) == 1 || PowerMod[2, #, d] == 1 &] (* _Amiram Eldar_, Jul 30 2020 *)

%o (PARI) isok(n) = !((2^n-1) % hammingweight(n)); \\ _Michel Marcus_, Nov 29 2013

%o (Python)

%o from itertools import count, islice

%o def A074202_gen(startvalue=1): # generator of terms >= startvalue

%o return filter(lambda n:not ((1<<n)-1) % n.bit_count(), count(max(startvalue,1)))

%o A074202_list = list(islice(A074202_gen(),20)) # _Chai Wah Wu_, Mar 09 2023

%Y Cf. A000120, A000225, A074203, A074293.

%Y Different from A128309.

%K base,easy,nonn

%O 1,2

%A _Benoit Cloitre_, Sep 17 2002

%E Edited by _N. J. A. Sloane_, May 10 2007

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Last modified April 25 13:12 EDT 2024. Contains 371969 sequences. (Running on oeis4.)