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 A064143 #13 Dec 14 2024 14:42:55
%S A064143 0,2,3,5,7,5,12,14,9,7,23,21,27,27,29,31,48,46,62,60,59,59,81,79,66,
%T A064143 66,59,59,93,93,124,126,120,118,125,123,141,141,158,156,193,193,225,
%U A064143 225,194,194,243,241,241,241,245,245,298,298,321,321,314,314,365,365,395
%N A064143 Sum of unitary prime divisors of binomial(n, floor(n/2)).
%H A064143 Harry J. Smith, <a href="/A064143/b064143.txt">Table of n, a(n) for n = 1..1000</a>
%F A064143 a(n) = A063956(A001405(n)).
%o A064143 (PARI) a(n) = { my(f=factor(binomial(n, n\2))); sum(i=1, #f~, if (f[i,2]==1, f[i,1])) } \\ _Harry J. Smith_, Sep 09 2009
%Y A064143 Cf. A001405, A008472, A034444, A056169, A063956.
%K A064143 nonn
%O A064143 1,2
%A A064143 _Labos Elemer_, Sep 11 2001