A061531 - OEIS

%I #10 Jun 11 2022 01:20:43

%S 1,2,2,1,3,10,37,173,865,4987,31695,222088,1696285,14039493,125126705,

%T 1194880848,12170926545,131720400008,1509404188204,18257416121656,

%U 232460634872927,3107769796958470,43526289269263574,637323017146341113

%N Boustrophedon transform of b(0)=1 and otherwise b(n)=mu(n).

%H <a href="/index/Bo#boustrophedon">Index entries for sequences related to boustrophedon transform</a>

%e a(5) = 10+mu(4) = (9+1)+0 = (6+3)+1+0 = (2+4)+4+0 = (-1+3)+8+0 = mu(5)+a(4)+8+mu(4).

%o (Python)

%o from itertools import count, islice, accumulate

%o from sympy import mobius

%o def A061531_gen(): # generator of terms

%o     blist, m = tuple(), 1

%o     for i in count(1):

%o         yield (blist := tuple(accumulate(reversed(blist),initial=m)))[-1]

%o         m = mobius(i)

%o A061531_list = list(islice(A061531_gen(),20)) # _Chai Wah Wu_, Jun 11 2022

%Y mu(n) = A008683(n) = ((-1)^A001221(n))*(0^(A001222(n)-A001221(n))).

%K easy,nonn

%O 0,2

%A _Frank Ellermann_, Jun 13 2001