cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A216176 Inner product of the Zeckendorf binary representation of n and its reverse.

Original entry on oeis.org

1, 0, 0, 2, 0, 2, 0, 0, 2, 0, 1, 3, 0, 2, 0, 0, 2, 0, 2, 0, 0, 2, 0, 0, 2, 1, 3, 1, 0, 2, 0, 2, 4, 0, 2, 0, 0, 2, 0, 2, 0, 0, 2, 0, 0, 2, 0, 2, 0, 2, 4, 0, 2, 0, 0, 2, 0, 0, 2, 0, 2, 0, 1, 3, 1, 1, 3, 0, 2, 0, 0, 2, 2, 4, 2, 0, 2, 0, 2, 4, 0, 2, 0, 1, 3, 1
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 10 2013

Keywords

Comments

a(n) = sum (A189920(n,k) * A213676(n,k): k = 1..A072649(n));
a(A027941(n)) = n.

Crossrefs

Cf. A159780.

Programs

  • Haskell
    a216176 n = sum $ zipWith (*) zs $ reverse zs
       where zs = a189920_row n

A227351 Permutation of nonnegative integers: map each number by lengths of runs of zeros in its Zeckendorf expansion shifted once left to the number which has the same lengths of runs (in the same order, but alternatively of runs of 0's and 1's) in its binary representation.

Original entry on oeis.org

0, 1, 3, 7, 2, 15, 6, 4, 31, 14, 12, 8, 5, 63, 30, 28, 24, 13, 16, 9, 11, 127, 62, 60, 56, 29, 48, 25, 27, 32, 17, 19, 23, 10, 255, 126, 124, 120, 61, 112, 57, 59, 96, 49, 51, 55, 26, 64, 33, 35, 39, 18, 47, 22, 20, 511, 254, 252, 248, 125, 240, 121, 123, 224
Offset: 0

Views

Author

Antti Karttunen, Jul 08 2013

Keywords

Comments

This permutation is based on the fact that by appending one extra zero to the right of Fibonacci number representation of n (aka "Zeckendorf expansion") and then counting the lengths of blocks of consecutive (nonleading) zeros we get bijective correspondence with compositions, and thus also with the binary representation of a unique n. See the chart below:
n A014417(n) A014417(A022342(n+1)) Runs of Binary number In dec.
[shifted once left] zeros with same runs = a(n)
0: ......0 ......0 [] .....0 0
1: ......1 .....10 [1] .....1 1
2: .....10 ....100 [2] ....11 3
3: ....100 ...1000 [3] ...111 7
4: ....101 ...1010 [1,1] ....10 2
5: ...1000 ..10000 [4] ..1111 15
6: ...1001 ..10010 [2,1] ...110 6
7: ...1010 ..10100 [1,2] ...100 4
8: ..10000 .100000 [5] .11111 31
9: ..10001 .100010 [3,1] ..1110 14
10: ..10010 .100100 [2,2] ..1100 12
11: ..10100 .101000 [1,3] ..1000 8
12: ..10101 .101010 [1,1,1] ...101 5
13: .100000 1000000 [6] 111111 63
Are there any other fixed points after 0, 1, 6, 803, 407483 ?

Crossrefs

Inverse permutation: A227352. Cf. also A003714, A014417, A006068, A048679.
Could be further composed with A075157 or A075159, also A129594.

Programs

Formula

a(n) = A006068(A048679(n)) = A006068(A106151(2*A003714(n))).
This permutation effects following correspondences:
a(A000045(n)) = A000225(n-1).
a(A027941(n)) = A000975(n).
For n >=3, a(A000204(n)) = A000079(n-2).

A371590 Irregular table T(n, k), n >= 0, k = 1..max(2, 2^n), read by rows; the n-th row lists the nonnegative numbers whose Zeckendorf-binary representation has n nonleading zeros.

Original entry on oeis.org

0, 1, 2, 4, 3, 6, 7, 12, 5, 9, 10, 11, 17, 19, 20, 33, 8, 14, 15, 16, 18, 25, 27, 28, 30, 31, 32, 46, 51, 53, 54, 88, 13, 22, 23, 24, 26, 29, 38, 40, 41, 43, 44, 45, 48, 49, 50, 52, 67, 72, 74, 75, 80, 82, 83, 85, 86, 87, 122, 135, 140, 142, 143, 232
Offset: 0

Views

Author

Rémy Sigrist, Mar 28 2024

Keywords

Comments

As a flat sequence, this is a permutation of the nonnegative integers with inverse A371591.

Examples

			Array T(n, k) begins:
    0, 1
    2, 4
    3, 6, 7, 12
    5, 9, 10, 11, 17, 19, 20, 33
    8, 14, 15, 16, 18, 25, 27, 28, 30, 31, 32, 46, 51, 53, 54, 88
    ...
		

Crossrefs

See A371592 for a similar sequence.
Cf. A000045, A027941, A102364, A371591 (inverse).

Programs

  • PARI
    \\ See Links section.

Formula

A102364(T(n, k)) = n.
T(n, 1) = A000045(n + 2) for any n > 0.
T(n, max(2, 2^n)) = A027941(n + 1) for any n >= 0.

A077784 Numbers k such that (10^k - 1)/3 + 2*10^floor(k/2) is a palindromic wing prime (a.k.a. near-repdigit palindromic prime).

Original entry on oeis.org

3, 5, 35, 159, 237, 325, 355, 371, 481, 1649, 3641, 4709, 269623
Offset: 1

Views

Author

Patrick De Geest, Nov 16 2002

Keywords

Comments

Prime versus probable prime status and proofs are given in the author's table.
a(13) > 2*10^5. - Robert Price, Apr 03 2016

Examples

			5 is a term because (10^5 - 1)/3 + 2*10^2 = 33533.
		

References

  • C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.

Crossrefs

Programs

  • Mathematica
    Do[ If[ PrimeQ[(10^n + 6*10^Floor[n/2] - 1)/3], Print[n]], {n, 3, 4800, 2}] (* Robert G. Wilson v, Dec 16 2005 *)

Formula

a(n) = 2*A183175(n) + 1.

Extensions

Name corrected by Jon E. Schoenfield, Oct 31 2018
a(13) from Robert Price, Aug 03 2024

A077828 Expansion of 1/(1-3*x-3*x^2-3*x^3).

Original entry on oeis.org

1, 3, 12, 48, 189, 747, 2952, 11664, 46089, 182115, 719604, 2843424, 11235429, 44395371, 175422672, 693160416, 2738935377, 10822555395, 42763953564, 168976333008, 667688525901, 2638286437419, 10424853888984, 41192486556912, 162766880649945, 643152663287523
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2002

Keywords

Crossrefs

Partial sums of S(n, x), for x=1...12, A021823, A000217, A027941, A061278, A089817, A053142, A092521, A076765, A092420, A097784, A097826-7.
Cf. A071675.

Programs

  • Mathematica
    CoefficientList[Series[1/(1-3x-3x^2-3x^3),{x,0,30}],x] (* or *) LinearRecurrence[ {3,3,3},{1,3,12},30] (* Harvey P. Dale, Dec 25 2018 *)
  • PARI
    Vec(1/(1-3*x-3*x^2-3*x^3)+O(x^99)) \\ Charles R Greathouse IV, Sep 27 2012

Formula

a(n) = sum{k=0..n, T(n-k, k)3^(n-k)}, T(n, k) = trinomial coefficients (A027907). - Paul Barry, Feb 15 2005
a(n) = sum{k=0..n, sum{i=0..floor((n-k)/2), C(n-k-i, i)C(k, n-k-i)}*3^k}. - Paul Barry, Apr 26 2005

A077829 Expansion of 1/(1-3*x-3*x^2-2*x^3).

Original entry on oeis.org

1, 3, 12, 47, 183, 714, 2785, 10863, 42372, 165275, 644667, 2514570, 9808261, 38257827, 149227404, 582072215, 2270414511, 8855914986, 34543132921, 134737972743, 525555146964, 2049965624963, 7996038261267, 31189121952618, 121655411891581, 474525678055131
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2002

Keywords

Crossrefs

Partial sums of S(n, x), for x=1...14, A021823, A000217, A027941, A061278, A089817, A053142, A092521, A076765, A092420, A097784, A097826-A097828, A076139.

Programs

  • Mathematica
    CoefficientList[Series[1/(1 - 3*x - 3*x^2 - 2*x^3), {x, 0, 30}], x] (* Wesley Ivan Hurt, Jan 20 2024 *)
    LinearRecurrence[{3,3,2},{1,3,12},30] (* Harvey P. Dale, Dec 20 2024 *)
  • PARI
    Vec(1/(1-3*x-3*x^2-2*x^3)+O(x^99)) \\ Charles R Greathouse IV, Sep 27 2012

Formula

G.f.: 1/(1-3*x-3*x^2-2*x^3).
a(n) = 3*a(n-1) + 3*a(n-2) + 2*a(n-3). - Wesley Ivan Hurt, Jan 20 2024

A077831 Expansion of 1/(1-3*x-2*x^2-2*x^3).

Original entry on oeis.org

1, 3, 11, 41, 151, 557, 2055, 7581, 27967, 103173, 380615, 1404125, 5179951, 19109333, 70496151, 260067021, 959412031, 3539362437, 13057045415, 48168685181, 177698871247, 655548074933, 2418379337655, 8921631905325, 32912750541151, 121418274109413
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2002

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[1/(1-3x-2x^2-2x^3),{x,0,30}],x] (* or *) LinearRecurrence[{3,2,2},{1,3,11},30] (* Harvey P. Dale, Feb 28 2025 *)
  • PARI
    Vec(1/(1-3*x-2*x^2-2*x^3)+O(x^99)) \\ Charles R Greathouse IV, Sep 27 2012

A143952 Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n having k peak plateaux (0<=k<=floor(n/2)). A peak plateau is a run of consecutive peaks that is preceded by an upstep and followed by a down step; a peak consists of an upstep followed by a downstep.

Original entry on oeis.org

1, 1, 1, 1, 1, 4, 1, 12, 1, 1, 33, 8, 1, 88, 42, 1, 1, 232, 183, 13, 1, 609, 717, 102, 1, 1, 1596, 2622, 624, 19, 1, 4180, 9134, 3275, 205, 1, 1, 10945, 30691, 15473, 1650, 26, 1, 28656, 100284, 67684, 11020, 366, 1, 1, 75024, 320466, 279106, 64553, 3716, 34, 1
Offset: 0

Views

Author

Emeric Deutsch, Oct 10 2008

Keywords

Comments

Row n has 1+floor(n/2) terms.
Row sums are the Catalan numbers (A000108).
T(n,1)=A027941(n-1)=Fibonacci(2n-1)-1.
Sum(k*T(n,k),k=0..floor(n/2))=A079309(n-1).
For the statistic "number of peaks in peak plateaux", see A143953.

Examples

			T(3,1)=4 because we have UD(UUDD), (UUDD)UD, (UUDUDD) and U(UUDD)D (the peak plateaux are shown between parentheses).
The triangle starts:
1;
1;
1,1;
1,4;
1,12,1;
1,33,8;
1,88,42,1;
		

Crossrefs

Programs

  • Maple
    C:=proc(z) options operator, arrow: (1/2-(1/2)*sqrt(1-4*z))/z end proc: G:=(1-z)*C(z*(1-z)^2/(1-z+z^2-t*z^2)^2)/(1-z+z^2-t*z^2): Gser:=simplify(series(G,z= 0,17)): for n from 0 to 14 do P[n]:=sort(coeff(Gser,z,n)) end do: for n from 0 to 14 do seq(coeff(P[n],t,j),j=0..floor((1/2)*n)) end do; # yields sequence in triangular form

Formula

The g.f. G=G(t,z) satisfies z(1-z)G^2 - (1-z+z^2-tz^2)G+1-z = 0 (for the explicit form of G see the Maple program).
The trivariate g.f. g=g(x,y,z) of Dyck paths with respect to number of peak plateaux, number of peaks in the peak plateaux and semilength, marked, by x, y and z, respectively satisfies g=1+zg[g+xyz/(1-yz)-z/(1-z)].
T(n,k) = Sum_{r=1..n} Narayana(n-r,k)*binomial(2n-r-k,r-k) where Narayana(n,k) := binomial(n,k)*binomial(n,k-1)/n is the Narayana number A001263. - David Callan, Oct 31 2008

A186025 a(n) = 0^n + 1 - F(n-1)^2 - F(n)^2, where F = A000045.

Original entry on oeis.org

1, 0, -1, -4, -12, -33, -88, -232, -609, -1596, -4180, -10945, -28656, -75024, -196417, -514228, -1346268, -3524577, -9227464, -24157816, -63245985, -165580140, -433494436, -1134903169, -2971215072, -7778742048, -20365011073, -53316291172, -139583862444
Offset: 0

Views

Author

Paul Barry, Feb 10 2011

Keywords

Comments

Row sums of number triangle A186024.

Crossrefs

Programs

  • Magma
    [0^n+1-Fibonacci(n-1)^2-Fibonacci(n)^2: n in [0..30]]; // Vincenzo Librandi, Apr 24 2015
    
  • Mathematica
    Join[{1}, Table[0^n + 1 - Fibonacci[n - 1]^2 - Fibonacci[n]^2, {n, 30}]] (* Vincenzo Librandi, Apr 24 2015 *)
    LinearRecurrence[{4,-4,1},{1,0,-1,-4},30] (* Harvey P. Dale, Dec 16 2015 *)
  • PARI
    x='x+O('x^50); Vec((1-4*x+3*x^2-x^3)/(1-4*x+4*x^2-x^3)) \\ G. C. Greubel, Jul 24 2017

Formula

G.f.: (1-4x+3x^2-x^3)/(1-4x+4x^2-x^3) = (1-4x+3x^2-x^3)/((1-x)(1-3x+x^2)).
a(n) = -A027941(n-1), n>0. - R. J. Mathar, Mar 21 2013

Extensions

More terms from Vincenzo Librandi, Apr 24 2015

A190757 Lucas Aurifeuillian primitive part A of Lucas(10*n - 5).

Original entry on oeis.org

1, 1, 101, 71, 181, 39161, 24571, 12301, 1158551, 87382901, 21211, 373270451, 28143378001, 32414581, 1322154751061, 9062194370461, 1550853481, 2819407321151, 265272771839851, 2366632711, 137083914639998701, 85417012034751151, 3455782010101
Offset: 1

Views

Author

Arkadiusz Wesolowski, Dec 29 2012

Keywords

Crossrefs

Programs

  • Mathematica
    lst = {1}; n = 23; Do[f = LucasL[k]; Do[f = f/GCD[f, lst[[d]]], {d, Most@Divisors[k]}]; AppendTo[lst, f], {k, 2, 10*n - 5}]; Table[GCD[lst[[5*k]], 5*Fibonacci[k]*(Fibonacci[k] - 1) + 1], {k, 1, 2*n - 1, 2}]

Formula

a(n) = GCD(A061447(10*n-5), A027941(n-1)*A106729(n-1) + 1).
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