A001025
Powers of 16: a(n) = 16^n.
Original entry on oeis.org
1, 16, 256, 4096, 65536, 1048576, 16777216, 268435456, 4294967296, 68719476736, 1099511627776, 17592186044416, 281474976710656, 4503599627370496, 72057594037927936, 1152921504606846976, 18446744073709551616, 295147905179352825856, 4722366482869645213696, 75557863725914323419136, 1208925819614629174706176
Offset: 0
- N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
- Muniru A Asiru, Table of n, a(n) for n = 0..820 (terms n = 0..100 from T. D. Noe)
- P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.
- INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 280
- Tanya Khovanova, Recursive Sequences
- Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
- Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992
- Y. Puri and T. Ward, Arithmetic and growth of periodic orbits, J. Integer Seqs., Vol. 4 (2001), #01.2.1.
- Index entries for linear recurrences with constant coefficients, signature (16).
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List([0..20],n->16^n); # Muniru A Asiru, Nov 07 2018
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a001025 = (16 ^)
a001025_list = iterate (* 16) 1 -- Reinhard Zumkeller, Nov 07 2012
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A001025:=-1/(-1+16*z); # Simon Plouffe in his 1992 dissertation
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Table[4^(2*n), {n,0,20}] (* Vladimir Joseph Stephan Orlovsky, Mar 01 2009 *)
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A001025(n):=16^n$
makelist(A001025(n),n,0,30); /* Martin Ettl, Nov 05 2012 */
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a(n)=1<<(4*n) \\ Charles R Greathouse IV, Feb 01 2012
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print([16**n for n in range(20)]) # Stefano Spezia, Nov 10 2018
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[lucas_number1(n,16,0) for n in range(1, 18)] # Zerinvary Lajos, Apr 29 2009
A386811
a(n) = Sum_{k=0..n} binomial(4*n+1,k).
Original entry on oeis.org
1, 6, 46, 378, 3214, 27896, 245506, 2182396, 19548046, 176142312, 1594831736, 14497410186, 132224930146, 1209397179048, 11088872706188, 101890087382168, 937973964234638, 8649109175873288, 79872298511230120, 738583466508887304, 6837944227813170424
Offset: 0
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[&+[Binomial(4*n+1, k): k in [0..n]]: n in [0..25]]; // Vincenzo Librandi, Aug 21 2025
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Table[Sum[Binomial[4*n+1,k], {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Aug 07 2025 *)
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a(n) = sum(k=0, n, binomial(4*n+1, k));
A216702
a(n) = Product_{k=1..n} (16 - 4/k).
Original entry on oeis.org
1, 12, 168, 2464, 36960, 561792, 8614144, 132903936, 2060011008, 32044615680, 499896004608, 7816555708416, 122459372765184, 1921670157238272, 30197673899458560, 475110069351481344, 7482983592285831168, 117967035454858985472, 1861257670509997326336
Offset: 0
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seq(product(16-4/k, k=1.. n), n=0..20);
seq((4^n/n!)*product(4*k+3, k=0.. n-1), n=0..20);
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Table[Product[16-4/k,{k,n}],{n,0,20}] (* or *) CoefficientList[ Series[ 1/(1-16*x)^(3/4),{x,0,20}],x] (* Harvey P. Dale, Sep 19 2012 *)
A244038
a(n) = 4^n * binomial(3*n/2,n).
Original entry on oeis.org
1, 6, 48, 420, 3840, 36036, 344064, 3325608, 32440320, 318704100, 3148873728, 31256180280, 311452237824, 3113596420200, 31213674823680, 313672599360720, 3158823892156416, 31870058661517860, 322076161553203200, 3259691964853493400, 33034843349204336640, 335189468043077792760
Offset: 0
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[Round(4^n*Gamma(3*n/2+1)/(Gamma(n+1)*Gamma(n/2+1))): n in [0..40]]; // G. C. Greubel, Aug 06 2018
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f1:=n->4^n*binomial(3*n/2,n); [seq(f1(n),n=0..40)];
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Table[4^n Binomial[3 n/2, n], {n, 0, 40}] (* Vincenzo Librandi, Jun 29 2014 *)
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{a(n) = if( n<1, n==0, 3^n * polcoeff( serreverse( x / (x+1) / 2 * sqrt((x+3) / (x+1) / 3 + x * O(x^n))), n))}; /* Michael Somos, Jan 27 2018 */
A034385
Expansion of (1-16*x)^(-1/4), related to quartic factorial numbers.
Original entry on oeis.org
1, 4, 40, 480, 6240, 84864, 1188096, 16972800, 246105600, 3609548800, 53421322240, 796463349760, 11946950246400, 180123249868800, 2727580640870400, 41459225741230080, 632253192553758720
Offset: 0
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CoefficientList[Series[1/Surd[1-16x,4],{x,0,20}],x] (* Harvey P. Dale, Aug 06 2018 *)
A386897
a(n) = 4^n * binomial(5*n/2,n).
Original entry on oeis.org
1, 10, 160, 2860, 53760, 1040060, 20500480, 409404600, 8255569920, 167718033340, 3427543285760, 70384350760360, 1451115518361600, 30018413447053080, 622759359440486400, 12951795276279787760, 269947721071617638400, 5637113741080428839100
Offset: 0
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Table[Sum[2^k *(-1)^(n-k)*Binomial[5*n+1, k]*Binomial[2*n-k, n-k], {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Aug 07 2025 *)
A386897[n_] := 4^n*Binomial[5*n/2, n]; Array[A386897, 20, 0] (* Paolo Xausa, Aug 26 2025 *)
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a(n) = 4^n*binomial(5*n/2, n);
Original entry on oeis.org
1, 2, 8, 16, 96, 192, 1280, 2560, 17920, 35840, 258048, 516096, 3784704, 7569408, 56229888, 112459776, 843448320, 1686896640, 12745441280, 25490882560, 193730707456, 387461414912, 2958796259328, 5917592518656, 45368209309696, 90736418619392, 697972450918400
Offset: 0
A174301
A symmetrical triangle: T(n,k) = binomial(n, k)*if(floor(n/2) greater than or equal to k then 4^k, otherwise 4^(n-k)).
Original entry on oeis.org
1, 1, 1, 1, 8, 1, 1, 12, 12, 1, 1, 16, 96, 16, 1, 1, 20, 160, 160, 20, 1, 1, 24, 240, 1280, 240, 24, 1, 1, 28, 336, 2240, 2240, 336, 28, 1, 1, 32, 448, 3584, 17920, 3584, 448, 32, 1, 1, 36, 576, 5376, 32256, 32256, 5376, 576, 36, 1, 1, 40, 720, 7680, 53760, 258048, 53760, 7680, 720, 40, 1
Offset: 0
Triangle begins:
1;
1, 1;
1, 8, 1;
1, 12, 12, 1;
1, 16, 96, 16, 1;
1, 20, 160, 160, 20, 1;
1, 24, 240, 1280, 240, 24, 1;
1, 28, 336, 2240, 2240, 336, 28, 1;
1, 32, 448, 3584, 17920, 3584, 448, 32, 1;
1, 36, 576, 5376, 32256, 32256, 5376, 576, 36, 1;
1, 40, 720, 7680, 53760, 258048, 53760, 7680, 720, 40, 1;
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[[Floor(n/2) ge k select 4^k*Binomial(n,k) else 4^(n-k)*Binomial(n,k): k in [0..n]]: n in [0..10]]; // G. C. Greubel, Apr 15 2019
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Table[Binomial[n, m]*If[Floor[n/2]>=m , 4^m, 4^(n-m)], {n,0,10}, {m,0,n} ]//Flatten
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{T(n,k) = binomial(n,k)*if(floor(n/2)>=k, 4^k, 4^(n-k))}; \\ G. C. Greubel, Apr 15 2019
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def T(n,k):
if floor(n/2)>=k: return 4^k*binomial(n,k)
else: return 4^(n-k)*binomial(n,k)
[[T(n,k) for k in (0..n)] for n in (0..10)] # G. C. Greubel, Apr 15 2019
A253665
a(n) = 2^n*n!/(floor(n/2)!)^2.
Original entry on oeis.org
1, 2, 8, 48, 96, 960, 1280, 17920, 17920, 322560, 258048, 5677056, 3784704, 98402304, 56229888, 1686896640, 843448320, 28677242880, 12745441280, 484326768640, 193730707456, 8136689713152, 2958796259328, 136104627929088, 45368209309696, 2268410465484800
Offset: 0
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a := n -> 2^n*n!/iquo(n,2)!^2: seq(a(n), n=0..25);
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Table[2^n*n!/Floor[n/2]!^2, {n, 0, 25}] (* Michael De Vlieger, Feb 02 2015 *)
CoefficientList[Series[(1 + 2 (1 - 8 x) x)/(1 - 16 x^2)^(3/2), {x, 0, 20}],x] (* Benedict W. J. Irwin, Aug 15 2016 *)
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a(n)=2^n*n!/(n\2)!^2 \\ Charles R Greathouse IV, Aug 25 2016
Original entry on oeis.org
1, 8, 80, 896, 10752, 135168, 1757184, 23429120, 318636032, 4402970624, 61641588736, 872465563648, 12463793766400, 179478630236160, 2602440138424320, 37965009078190080, 556820133146787840, 8205770383215820800, 121445401671594147840, 1804331681977970196480, 26900945076762464747520
Offset: 0
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[4^n*Catalan(n+1): n in [0..25]]; // Vincenzo Librandi, Apr 25 2016
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Table[4^n CatalanNumber[n + 1], {n, 0, 20}] (* Bruno Berselli, Mar 07 2016 *)
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cat(n) = binomial(2*n,n)/(n+1);
a(n) = 4^n*cat(n+1);
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[4^n*catalan_number(n+1) for n in (0..20)] # Bruno Berselli, Mar 07 2016
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