A364548 - OEIS

%I #5 Jul 28 2023 16:35:40

%S 1,2,3,4,5,6,8,10,12,16,20,24,32,40,48,64,80,96,97,128,160,192,194,

%T 256,320,345,384,388,512,549,640,690,768,776,1024,1093,1098,1280,1380,

%U 1536,1552,2048,2186,2196,2560,2760,3072,3104,4096,4372,4392,5120,5520,6144,6208,8192,8744,8784,10240,11040,12288,12416,16384

%N Numbers k such that k divides A005941(k).

%C Numbers k such that k divides 1+A156552(k).

%C Sequence A005940(A364546(.)) sorted into ascending order.

%C If k is a term, then also 2*k is present in this sequence, and vice versa.

%o (PARI)

%o A005941(n) = { my(f=factor(n), p, p2=1, res=0); for(i=1, #f~, p = 1 << (primepi(f[i, 1])-1); res += (p * p2 * (2^(f[i, 2])-1)); p2 <<= f[i, 2]); (1+res) }; \\ (After _David A. Corneth_'s program for A156552)

%o isA364548(n) = !(A005941(n)%n);

%Y Cf. A005940, A005941, A156552, A364546.

%Y Subsequences: A029747, A364549 (odd terms).

%Y Cf. also A364497.

%K nonn

%O 1,2

%A _Antti Karttunen_, Jul 28 2023