cp's OEIS Frontend

A230955 Boustrophedon transform of nonprimes.

%I A230955 #19 Jun 12 2022 14:05:57
%S A230955 1,5,15,40,114,371,1422,6334,32238,184655,1175454,8231308,62882262,
%T A230955 520416569,4638303786,44292536061,451160065069,4882696090609,
%U A230955 55951575728713,676777708544967,8617001415386120,115200823068725262,1613460678695102980,23624702309844184487
%N A230955 Boustrophedon transform of nonprimes.
%H A230955 Reinhard Zumkeller, <a href="/A230955/b230955.txt">Table of n, a(n) for n = 0..400</a>
%H A230955 Peter Luschny, <a href="http://oeis.org/wiki/User:Peter_Luschny/SeidelTransform">An old operation on sequences: the Seidel transform</a>
%H A230955 J. Millar, N. J. A. Sloane and N. E. Young, A new operation on sequences: the Boustrophedon transform, J. Combin. Theory, 17A 44-54 1996 (<a href="http://neilsloane.com/doc/bous.txt">Abstract</a>, <a href="http://neilsloane.com/doc/bous.pdf">pdf</a>, <a href="http://neilsloane.com/doc/bous.ps">ps</a>).
%H A230955 Wikipedia, <a href="http://en.wikipedia.org/wiki/Boustrophedon_transform">Boustrophedon transform</a>
%H A230955 <a href="/index/Bo#boustrophedon">Index entries for sequences related to boustrophedon transform</a>
%F A230955 a(n) = Sum_{k=0..n} A109449(n,k)*A018252(k+1).
%t A230955 cc = Select[Range[max = 40], !PrimeQ[#]&]; t[n_, 0] := cc[[n+1]]; t[n_, k_] := t[n, k] = t[n, k-1] + t[n-1, n-k]; a[n_] := t[n, n]; Array[a, cc // Length, 0] (* _Jean-François Alcover_, Feb 12 2016 *)
%o A230955 (Haskell)
%o A230955 a230955 n = sum $ zipWith (*) (a109449_row n) a018252_list
%o A230955 (Python)
%o A230955 from itertools import accumulate, count, islice
%o A230955 from sympy import composite
%o A230955 def A230955_gen(): # generator of terms
%o A230955     yield 1
%o A230955     blist = (1,)
%o A230955     for i in count(1):
%o A230955         yield (blist := tuple(accumulate(reversed(blist),initial=composite(i))))[-1]
%o A230955 A230955_list = list(islice(A230955_gen(),40)) # _Chai Wah Wu_, Jun 12 2022
%Y A230955 Cf. A230954, A000747, A000732, A230953.
%K A230955 nonn
%O A230955 0,2
%A A230955 _Reinhard Zumkeller_, Nov 03 2013