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Sequence shifts left four places under Weigh transform with a(n) = signum(n) for n<4.
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%I #10 May 09 2019 06:58:20

%S 0,1,1,1,1,1,1,2,2,3,4,6,8,12,18,26,39,58,88,133,202,308,472,725,1116,

%T 1725,2669,4141,6437,10027,15643,24448,38265,59979,94143,147953,

%U 232799,366725,578311,912913,1442503,2281429,3611406,5721528,9071789,14394837

%N Sequence shifts left four places under Weigh transform with a(n) = signum(n) for n<4.

%H Alois P. Heinz, <a href="/A316076/b316076.txt">Table of n, a(n) for n = 0..2000</a>

%F G.f.: x + x^2 + x^3 + x^4 * Product_{n>=1} (1 + x^n)^a(n). - _Ilya Gutkovskiy_, May 09 2019

%p b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,

%p add(binomial(a(i), j)*b(n-i*j, i-1), j=0..n/i)))

%p end:

%p a:= n-> (k-> `if`(n<k, signum(n), b(n-k$2)))(4):

%p seq(a(n), n=0..45);

%Y Column k=4 of A316074.

%Y Cf. A057427, A218021.

%K nonn,eigen

%O 0,8

%A _Alois P. Heinz_, Jun 23 2018