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A186431 Row sums of A186430.

%I A186431 #24 Jun 26 2019 03:33:56
%S A186431 1,2,4,26,18,482,266,6050,3114,21122,10730,22178,11226,4455362,
%T A186431 2256338,343874,173610,13643522,6869842,690621122,347772738,
%U A186431 16250361602,8187307306,17146915106,8584448890,720152334722,365024665978,59381983394,29700003082
%N A186431 Row sums of A186430.
%F A186431 a(n) = Sum_{k=0..n} A053657(n)/(A053657(k)*A053657(n-k)), with the convention that A053657(0) = 1.
%p A186431 # A186431, uses program for A053657 written by Peter Luschny:
%p A186431 A053657 := proc(n) local P, p, q, s, r;
%p A186431 P := select(isprime, [$2..n]); r:=1;
%p A186431 for p in P do s := 0; q := p-1;
%p A186431 do if q > (n-1) then break fi;
%p A186431 s := s + iquo(n-1, q); q := q*p; od;
%p A186431 r := r * p^s; od; r end:
%p A186431 # Row sums:
%p A186431 a:= n-> add(A053657(n)/(A053657(k)*A053657(n-k)), k = 0..n):
%p A186431 seq (a(n), n = 0..22);
%t A186431 b[n_] := b[n] = Product[p^Sum[Floor[(n-1)/((p-1) p^k)], {k, 0, n}], {p, Prime[ Range[n]]}];
%t A186431 T[n_, k_] := b[n]/(b[k] b[n-k]);
%t A186431 a[n_] := Sum[T[n, k], {k, 0, n}];
%t A186431 Table[a[n], {n, 0, 28}] (* _Jean-François Alcover_, Jun 26 2019 *)
%Y A186431 Cf. A053657, A186430.
%K A186431 nonn,easy
%O A186431 0,2
%A A186431 _Peter Bala_, Feb 21 2011