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A188541 a(n) = A079500(n) - 2*A079500(n-1). 2

%I

%S 1,0,1,1,2,2,4,5,9,14,24,40,70,120,211,371,658,1172,2102,3786,6856,

%T 12470,22782,41789,76947,142180,263578,490104,913858,1708386,3201290,

%U 6011962,11313274,21329276,40282947,76202831,144370582,273906268,520359324,989804122,1884992934,3593832942,6859139352,13104584156,25061042050,47971076906,91906883496

%N a(n) = A079500(n) - 2*A079500(n-1).

%C Arises in studying a conjecture related to lunar divisors in base 2.

%H Alois P. Heinz, <a href="/A188541/b188541.txt">Table of n, a(n) for n = 2..1000</a>

%H D. Applegate, M. LeBrun and N. J. A. Sloane, <a href="http://arxiv.org/abs/1107.1130">Dismal Arithmetic</a>, arXiv:1107.1130 [math.NT], 2011. [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]

%t b[n_, m_] := b[n, m] = If[n == 0, 1, If[m == 0, Sum[b[n-j, j], {j, 1, n}], Sum[b[n-j, Min[n-j, m]], {j, 1, Min[n, m]}]]];

%t a79500[n_] := b[n, 0];

%t a[n_] := -a79500[n-1] + 2 a79500[n-2];

%t Table[a[n], {n, 2, 48}] (* _Jean-Fran├žois Alcover_, Sep 15 2018, after _Alois P. Heinz_ in A079500 *)

%Y Cf. A079500.

%K nonn

%O 2,5

%A _N. J. A. Sloane_, Apr 03 2011

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Last modified September 21 23:55 EDT 2019. Contains 327286 sequences. (Running on oeis4.)