A144318 - OEIS

%I #8 Sep 17 2014 18:29:29

%S 1,1,16,256,4216,67456,1083136,17330176,277344816,4437547776,

%T 71001776256,1136028420096,18176471920896,290823550734336,

%U 4653177071702016,74450833163421696,1191213334782285596,19059413356516569536,304950613771087329536,4879209820337397272576

%N Shifts left when Dirichlet convolution (DC:(b,b)->a) applied 4 times.

%H Alois P. Heinz, <a href="/A144318/b144318.txt">Table of n, a(n) for n = 1..500</a>

%H N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>

%p k:=4: with (numtheory): dc:= proc(b,c) proc(n) option remember; add (b(d) *c(n/d), d=`if`(n<0,{}, divisors(n))) end end: a:='a': b[1]:= dc(a,a): for t from 2 to k do b[t]:= dc(b[t-1], b[t-1]) od: a:= n-> `if`(n=1, 1, b[k](n-1)): seq (a(n), n=1..30);

%Y 4th column of A144324.

%K eigen,nonn

%O 1,3

%A _Alois P. Heinz_, Sep 17 2008