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A049638 a(n) = T(n,4), array T as in A049627. 0

%I #11 Aug 06 2021 04:50:33

%S 2,7,9,12,14,18,19,23,25,28,30,34,35,39,41,44,46,50,51,55,57,60,62,66,

%T 67,71,73,76,78,82,83,87,89,92,94,98,99,103,105,108,110,114,115,119,

%U 121,124,126,130,131,135,137,140,142,146,147,151,153,156,158,162

%N a(n) = T(n,4), array T as in A049627.

%F Conjectured g.f.: 2 -x*(-7-9*x-5*x^2+2*x^3+3*x^4) / ( (1+x)*(1+x+x^2)*(x-1)^2 ). - _R. J. Mathar_, Oct 26 2015

%o (PARI) T(n,k) = (n+1)*(k+1) - sum(i=0, n, sum(j=0, k, gcd(i,j)>1)); \\ A049627

%o a(n) = T(n, 4); \\ _Michel Marcus_, Aug 06 2021

%Y Cf. A049627.

%K nonn

%O 0,1

%A _Clark Kimberling_

%E More terms from _Sean A. Irvine_, Aug 06 2021

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)