A186431 - OEIS

A186431

Row sums of A186430.

1, 2, 4, 26, 18, 482, 266, 6050, 3114, 21122, 10730, 22178, 11226, 4455362, 2256338, 343874, 173610, 13643522, 6869842, 690621122, 347772738, 16250361602, 8187307306, 17146915106, 8584448890, 720152334722, 365024665978, 59381983394, 29700003082

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..28.

FORMULA

a(n) = Sum_{k=0..n} A053657(n)/(A053657(k)*A053657(n-k)), with the convention that A053657(0) = 1.

MAPLE

# A186431, uses program for A053657 written by Peter Luschny:

A053657 := proc(n) local P, p, q, s, r;

P := select(isprime, [$2..n]); r:=1;

for p in P do s := 0; q := p-1;

do if q > (n-1) then break fi;

s := s + iquo(n-1, q); q := q*p; od;

r := r * p^s; od; r end:

# Row sums:

a:= n-> add(A053657(n)/(A053657(k)*A053657(n-k)), k = 0..n):

seq (a(n), n = 0..22);

MATHEMATICA

b[n_] := b[n] = Product[p^Sum[Floor[(n-1)/((p-1) p^k)], {k, 0, n}], {p, Prime[ Range[n]]}];

T[n_, k_] := b[n]/(b[k] b[n-k]);

a[n_] := Sum[T[n, k], {k, 0, n}];

Table[a[n], {n, 0, 28}] (* Jean-François Alcover, Jun 26 2019 *)

CROSSREFS

Cf. A053657, A186430.

Sequence in context: A162118 A128774 A218258 * A129894 A028386 A362001

Adjacent sequences: A186428 A186429 A186430 * A186432 A186433 A186434

KEYWORD

nonn,easy

AUTHOR

Peter Bala, Feb 21 2011

STATUS

approved