Original entry on oeis.org
4, 7, 19, 28, 64, 91, 199, 280, 604, 847, 1819, 2548, 5464, 7651, 16399, 22960, 49204, 68887, 147619, 206668, 442864, 620011, 1328599, 1860040, 3985804, 5580127, 11957419, 16740388, 35872264, 50221171, 107616799, 150663520, 322850404
Offset: 1
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T:=[ n le 2 select 5-n else 3*Self(n-2): n in [1..33] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];
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LinearRecurrence[{1,3,-3},{4,7,19},40] (* Harvey P. Dale, Aug 28 2016 *)
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a(n)=if(n%2,15,7)*3^(n\2)\2-3 \\ Charles R Greathouse IV, Jul 15 2011
A153594
a(n) = ((4 + sqrt(3))^n - (4 - sqrt(3))^n)/(2*sqrt(3)).
Original entry on oeis.org
1, 8, 51, 304, 1769, 10200, 58603, 336224, 1927953, 11052712, 63358307, 363181200, 2081791609, 11932977272, 68400527259, 392075513536, 2247397253921, 12882196355400, 73841406542227, 423262699717616, 2426163312691977, 13906891405206808
Offset: 1
Al Hakanson (hawkuu(AT)gmail.com), Dec 29 2008
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Z:= PolynomialRing(Integers()); N:=NumberField(x^2-3); S:=[ ((4+r)^n-(4-r)^n)/(2*r): n in [1..21] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Dec 31 2008
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I:=[1,8]; [n le 2 select I[n] else 8*Self(n-1)-13*Self(n-2): n in [1..25]]; // Vincenzo Librandi, Aug 23 2016
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Join[{a=1,b=8},Table[c=8*b-13*a;a=b;b=c,{n,60}]] (* Vladimir Joseph Stephan Orlovsky, Jan 19 2011 *)
LinearRecurrence[{8,-13},{1,8},40] (* Harvey P. Dale, Aug 16 2012 *)
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a(n)=([0,1; -13,8]^(n-1)*[1;8])[1,1] \\ Charles R Greathouse IV, Sep 04 2016
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[lucas_number1(n,8,13) for n in range(1, 22)] # Zerinvary Lajos, Apr 23 2009
A074324
a(2n+1) = 3^n, a(2n) = 4*3^(n-1) except for a(0) = 1.
Original entry on oeis.org
1, 1, 4, 3, 12, 9, 36, 27, 108, 81, 324, 243, 972, 729, 2916, 2187, 8748, 6561, 26244, 19683, 78732, 59049, 236196, 177147, 708588, 531441, 2125764, 1594323, 6377292, 4782969, 19131876, 14348907, 57395628, 43046721, 172186884, 129140163
Offset: 0
Y. Kelly Itakura (yitkr(AT)mta.ca), Aug 21 2002
nu(0)=1;
nu(1)=1;
nu(2)=4;
nu(3)=7+3q;
nu(4)=19+15q+12q^2;
nu(5)=40+45q+42q^2+30q^3+9q^4;
nu(6)=97+147q+180q^2+168q^3+147q^4+81q^5+36q^6;
by listing the coefficients of the highest power in each nu(n), we get, 1,1,4,3,12,9,36,....
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[1] cat [(1/6)*(7+(-1)^n)*3^Floor(n/2):n in [1..40]]; // Vincenzo Librandi, Jul 20 2013
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CoefficientList[Series[-(1 + x + x^2) / (-1 + 3 x^2), {x, 0, 40}], x] (* Vincenzo Librandi, Jul 20 2013 *)
LinearRecurrence[{0,3},{1,1,4},40] (* Harvey P. Dale, Mar 13 2016 *)
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a(n)=3^(n\2)\(3/4)^!bittest(n,0) \\ M. F. Hasler, Dec 03 2014
A162813
a(n) = 3*a(n-2) for n > 2; a(1) = 5, a(2) = 3.
Original entry on oeis.org
5, 3, 15, 9, 45, 27, 135, 81, 405, 243, 1215, 729, 3645, 2187, 10935, 6561, 32805, 19683, 98415, 59049, 295245, 177147, 885735, 531441, 2657205, 1594323, 7971615, 4782969, 23914845, 14348907, 71744535, 43046721, 215233605, 129140163, 645700815, 387420489
Offset: 1
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[ n le 2 select 7-2*n else 3*Self(n-2): n in [1..34] ];
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nxt[{a_,b_}]:={b,3a}; NestList[nxt,{5,3},40][[All,1]] (* or *) LinearRecurrence[ {0,3},{5,3},40] (* Harvey P. Dale, May 29 2021 *)
A162852
a(n) = 3*a(n-2) for n > 2; a(1) = 3, a(2) = -1.
Original entry on oeis.org
3, -1, 9, -3, 27, -9, 81, -27, 243, -81, 729, -243, 2187, -729, 6561, -2187, 19683, -6561, 59049, -19683, 177147, -59049, 531441, -177147, 1594323, -531441, 4782969, -1594323, 14348907, -4782969, 43046721, -14348907, 129140163
Offset: 1
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a:=[3,-1];; for n in [3..25] do a[n]:=3*a[n-2]; od; a; # Muniru A Asiru, Oct 25 2018
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[ n le 2 select 7-4*n else 3*Self(n-2): n in [1..34] ];
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seq(op([3^n,-3^(n-1)]),n=1..18); # Muniru A Asiru, Oct 25 2018
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Rest[CoefficientList[Series[x*(3-x)/(1-3*x^2), {x, 0, 40}], x]] (* or *) LinearRecurrence[{0,3}, {3,-1}, 40] (* G. C. Greubel, Oct 24 2018 *)
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x='x+O('x^40); Vec(x*(3-x)/(1-3*x^2)) \\ G. C. Greubel, Oct 24 2018
A166552
a(n) = 3*a(n-2) for n > 2; a(1) = 1; a(2) = 4.
Original entry on oeis.org
1, 4, 3, 12, 9, 36, 27, 108, 81, 324, 243, 972, 729, 2916, 2187, 8748, 6561, 26244, 19683, 78732, 59049, 236196, 177147, 708588, 531441, 2125764, 1594323, 6377292, 4782969, 19131876, 14348907, 57395628, 43046721, 172186884, 129140163
Offset: 1
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[ n le 2 select 3*n-2 else 3*Self(n-2): n in [1..35] ];
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LinearRecurrence[{0, 3}, {1, 4}, 50] (* G. C. Greubel, May 17 2016 *)
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a(n)=3^(n\2)*(4/3)^!bittest(n,0) \\ M. F. Hasler, Dec 03 2014
A162559
a(n) = ((4+sqrt(3))*(1+sqrt(3))^n + (4-sqrt(3))*(1-sqrt(3))^n)/2.
Original entry on oeis.org
4, 7, 22, 58, 160, 436, 1192, 3256, 8896, 24304, 66400, 181408, 495616, 1354048, 3699328, 10106752, 27612160, 75437824, 206099968, 563075584, 1538351104, 4202853376, 11482408960, 31370524672, 85705867264, 234152783872, 639717302272, 1747740172288, 4774914949120
Offset: 0
Al Hakanson (hawkuu(AT)gmail.com), Jul 06 2009
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Z:=PolynomialRing(Integers()); N:=NumberField(x^2-3); S:=[ ((4+r)*(1+r)^n+(4-r)*(1-r)^n)/2: n in [0..25] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Jul 13 2009
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seq((1/2)*simplify((4+sqrt(3))*(1+sqrt(3))^n+(4-sqrt(3))*(1-sqrt(3))^n), n = 0 .. 27); # Emeric Deutsch, Jul 16 2009
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LinearRecurrence[{2,2},{4,7},30] (* Harvey P. Dale, Sep 21 2018 *)
Two different extensions were received. This version was rechecked by
N. J. A. Sloane, Jul 19 2009
A162561
a(n) = ((4+sqrt(3))*(5+sqrt(3))^nv+v(4-sqrt(3))*(5-sqrt(3))^n)/2.
Original entry on oeis.org
4, 23, 142, 914, 6016, 40052, 268168, 1800536, 12105664, 81444848, 548123872, 3689452064, 24835795456, 167190009152, 1125512591488, 7576945713536, 51008180122624, 343388995528448, 2311709992586752, 15562542024241664
Offset: 0
Al Hakanson (hawkuu(AT)gmail.com), Jul 06 2009
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Z:=PolynomialRing(Integers()); N:=NumberField(x^2-3); S:=[ ((4+r)*(5+r)^n+(4-r)*(5-r)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Jul 14 2009
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LinearRecurrence[{10,-22},{4,23},30] (* Harvey P. Dale, Mar 27 2013 *)
A164311
a(n) = 12*a(n-1) - 33*a(n-2) for n > 1; a(0) = 4, a(1) = 27.
Original entry on oeis.org
4, 27, 192, 1413, 10620, 80811, 619272, 4764501, 36738036, 283627899, 2191179600, 16934434533, 130904287596, 1012015111563, 7824339848088, 60495579495477, 467743738958820, 3616570744155099, 27963305544220128, 216212831973523269
Offset: 0
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[ n le 2 select 23*n-19 else 12*Self(n-1)-33*Self(n-2): n in [1..20] ];
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LinearRecurrence[{12,-33}, {4,27}, 50] (* or *) CoefficientList[Series[(4 - 21*x)/(1 - 12*x + 33*x^2), {x,0,50}], x] (* G. C. Greubel, Sep 13 2017 *)
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x='x+O('x^50); Vec((4-21*x)/(1-12*x+33*x^2)) \\ G. C. Greubel, Sep 13 2017
Showing 1-9 of 9 results.
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