This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A067657 #22 Apr 07 2025 23:04:21
%S A067657 3,11,137,761,7129,18858053,34395742267,85691034670497533,
%T A067657 252476961434436524654789,928551009361054917576341971,
%U A067657 42409610330030873613929048033,4868007055309996043055960217131137
%N A067657 Prime values of A001008, the numerators of the harmonic numbers.
%C A067657 This sequence comprises the only primes for which 1/Sum_{k=1..c}(1/(a(n)*k)) is an integer for some c >= 2, yielding A002805(A056903(n)) for c = A056903(n). E.g. for n = 2: a(2) = 11, A056903(2) = 3, and 1 / (1/11 + 1/22 + 1/33) = 6 = A002805(A056903(2)). - _Charles L. Hohn_, Apr 02 2025
%H A067657 Amiram Eldar, <a href="/A067657/b067657.txt">Table of n, a(n) for n = 1..43</a>
%F A067657 A001008 INTERSECT A000040.
%F A067657 a(n) = A001008(A056903(n)). - _Amiram Eldar_, Jun 02 2022
%t A067657 Table[ HarmonicNumber[n], {n, 0, 80}] // Numerator // Select[#, PrimeQ]& (* _Jean-François Alcover_, May 27 2013 *)
%Y A067657 Cf. A001008, A056903.
%Y A067657 Cf. A002805.
%K A067657 nonn
%O A067657 1,1
%A A067657 _Benoit Cloitre_, Feb 03 2002