%I #11 Jan 06 2019 06:52:40
%S 1,4,9,32,71,252,559,1984,4401,15620,34649,122976,272791,968188,
%T 2147679,7622528,16908641,60012036,133121449,472473760,1048062951,
%U 3719778044,8251382159,29285750592,64962994321,230566226692,511452572409,1815244062944
%N First differences of A237262.
%H Colin Barker, <a href="/A322780/b322780.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,8,0,-1).
%F From _Colin Barker_, Jan 06 2019: (Start)
%F G.f.: x*(1 + 4*x + x^2) / (1 - 8*x^2 + x^4).
%F a(n) = 8*a(n-2) - a(n-4) for n>4.
%F (End)
%o (PARI) Vec(x*(1 + 4*x + x^2) / (1 - 8*x^2 + x^4) + O(x^40)) \\ _Colin Barker_, Jan 06 2019
%Y Cf. A237262, A199336.
%K nonn,easy
%O 1,2
%A _N. J. A. Sloane_, Jan 05 2019, following a suggestion from _Stan Wagon_.