A349477 - OEIS

%I #14 Feb 02 2023 06:23:42

%S 1,6,8,10,15,16,21,28,30,39,48,56,57,64,93,111,129,140,183,184,192,

%T 195,200,201,210,219,220,237,270,291,309,327,345,381,417,453,471,489,

%U 496,543,545,574,579,597,600,633,645,669,672,687,723,765,792,795,798,813

%N Numbers k such that the sequence of elements of the continued fraction of the harmonic mean of the divisors of k is palindromic.

%C All the harmonic numbers (A001599) are terms of this sequence.

%H Amiram Eldar, <a href="/A349477/b349477.txt">Table of n, a(n) for n = 1..10000</a>

%e 8 is a term since the sequence of elements of the continued fraction of the harmonic mean of the divisors of 8, 32/15 = 2 + 1/(7 + 1/2), is {2, 7, 2}, which is palindromic.

%t q[n_] := PalindromeQ[ContinuedFraction[DivisorSigma[0, n] / DivisorSigma[-1, n]]]; Select[Range[1000], q]

%Y A001599 and A349476 are subsequences.

%Y Cf. A099377, A099378, A349473.

%K nonn

%O 1,2

%A _Amiram Eldar_, Nov 19 2021