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 A064450 #19 Dec 14 2024 14:41:06
%S A064450 1,2,3,6,8,18,30,86,106,158,290,662,1410,3674,7166,16242,20242,46754,
%T A064450 72910,162686,304866,524570,1179430,2842710,5230210,11035402,24478394,
%U A064450 40473686,63927602,155016682,328928338,888801182,928681474,1765045802
%N A064450 Sum of totients of binomial coefficients C(n,j), j=0..n.
%C A064450 a(n) = sum of n-th row of the triangle formed by replacing each m in Pascal's triangle by phi(m). See A102715.
%H A064450 Harry J. Smith, <a href="/A064450/b064450.txt">Table of n, a(n) for n = 0..200</a>
%e A064450 For n=4, the binomial coefficients C(4,j) are 1, 4, 6, 4, and 1. The totients are 1, 2, 2, 2, and 1. So a(4) = 1 + 2 + 2 + 2 + 1 = 8. - _Michael B. Porter_, Jun 25 2018
%t A064450 a(n)=Apply[Plus, Table[EulerPhi[Binomial[n, w]], {w, 0, n}]],
%o A064450 (PARI) a(n) = vecsum(vector(n+1, k, eulerphi(binomial(n, k-1)))); \\ _Michel Marcus_, Jun 24 2018
%Y A064450 Cf. A000010, A102715.
%K A064450 nonn
%O A064450 0,2
%A A064450 _Labos Elemer_, Oct 02 2001