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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A223504 T(n,k)=Petersen graph (3,1) coloring a rectangular array: number of nXk 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,3 3,5 3,4 1,2 1,4 4,5 2,0 2,5 and every array movement to a horizontal, diagonal or antidiagonal neighbor moves along an edge of this graph, with the array starting at 0.

Original entry on oeis.org

1, 3, 6, 9, 19, 36, 27, 115, 121, 216, 81, 631, 1519, 771, 1296, 243, 3539, 16323, 20115, 4913, 7776, 729, 19759, 182901, 426359, 266419, 31307, 46656, 2187, 110427, 2030665, 9685063, 11148439, 3528715, 199497, 279936, 6561, 617015, 22598167
Offset: 1

Views

Author

R. H. Hardin Mar 21 2013

Keywords

Comments

Table starts
........1........3............9..............27.................81
........6.......19..........115.............631...............3539
.......36......121.........1519...........16323.............182901
......216......771........20115..........426359............9685063
.....1296.....4913.......266419........11148439..........515473927
.....7776....31307......3528715.......291545903........27465794119
....46656...199497.....46737819......7624417031......1463848507173
...279936..1271251....619042315....199391762123.....78024299447333
..1679616..8100769...8199214219...5214442630935...4158831849750231
.10077696.51620379.108598575915.136366781617267.221674060909378867

Examples

			Some solutions for n=3 k=4
..0..3..4..1....0..2..1..4....0..3..0..3....0..2..1..2....0..1..4..3
..0..3..4..3....5..2..5..4....4..1..0..1....1..2..0..2....0..1..0..3
..5..3..0..1....1..2..1..2....0..1..0..1....5..2..0..2....0..3..0..1
		

Crossrefs

Column 1 is A000400(n-1)
Column 2 is A138977
Row 1 is A000244(n-1)

Formula

Empirical for column k:
k=1: a(n) = 6*a(n-1)
k=2: a(n) = 7*a(n-1) -4*a(n-2)
k=3: a(n) = 15*a(n-1) -24*a(n-2) +10*a(n-3)
k=4: a(n) = 31*a(n-1) -127*a(n-2) -20*a(n-3) +705*a(n-4) -1027*a(n-5) +499*a(n-6) -60*a(n-7)
k=5: [order 21]
k=6: [order 53]
Empirical for row n:
n=1: a(n) = 3*a(n-1)
n=2: a(n) = 5*a(n-1) +4*a(n-2) -4*a(n-3) for n>4
n=3: a(n) = 12*a(n-1) -4*a(n-2) -73*a(n-3) +103*a(n-4) -23*a(n-5) -16*a(n-6) +4*a(n-7) for n>8
n=4: [order 21] for n>22
n=5: [order 60] for n>61

A240523 a(n) = floor(4^n/((1+sqrt(5))/2)^(2*n)).

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 12, 19, 29, 45, 69, 105, 161, 247, 377, 577, 881, 1347, 2058, 3144, 4805, 7341, 11216, 17137, 26183, 40005, 61122, 93387, 142682, 218000, 333074, 508892, 777518, 1187942, 1815014, 2773095, 4236913
Offset: 0

Views

Author

Kival Ngaokrajang, Apr 07 2014

Keywords

Comments

a(n) is the perimeter (rounded down) of pentaflake after n iterations, let a(0) = 1. The total number of sides is 5*A000302(n).

Crossrefs

Programs

  • Maple
    A240523:=n->floor(4^n/((1+sqrt(5))/2)^(2*n)); seq(A240523(n), n=0..50); # Wesley Ivan Hurt, Apr 07 2014
  • Mathematica
    Table[Floor[4^n/(((1 + Sqrt[5]))/2)^(2 n)], {n, 0, 50}] (* Wesley Ivan Hurt, Apr 07 2014 *)
    Table[Floor[4^n/GoldenRatio^(2n)],{n,0,40}] (* Harvey P. Dale, Mar 24 2018 *)
  • PARI
    a(n) = floor(4^n/((1+sqrt(5))/2)^(2*n))

Formula

Equals floor((2/(phi))^(2*n)), where phi is the golden ratio. - G. C. Greubel, Jul 05 2017

A322827 A permutation of A025487: Sequence of least representatives of distinct prime signatures obtained from the run lengths present in the binary expansion of n.

Original entry on oeis.org

1, 2, 6, 4, 36, 30, 12, 8, 216, 180, 210, 900, 72, 60, 24, 16, 1296, 1080, 1260, 5400, 44100, 2310, 6300, 27000, 432, 360, 420, 1800, 144, 120, 48, 32, 7776, 6480, 7560, 32400, 264600, 13860, 37800, 162000, 9261000, 485100, 30030, 5336100, 1323000, 69300, 189000, 810000, 2592, 2160, 2520, 10800, 88200, 4620, 12600
Offset: 0

Views

Author

Antti Karttunen, Jan 16 2019

Keywords

Comments

A101296(a(n)) gives a permutation of natural numbers.

Examples

			The sequence can be represented as a binary tree:
                                      1
                                      |
                   ...................2...................
                  6                                       4
       36......../ \........30                 12......../ \........8
       / \                 / \                 / \                 / \
      /   \               /   \               /   \               /   \
     /     \             /     \             /     \             /     \
   216      180         210    900         72       60         24       16
etc.
Both children are multiples of their common parent, see A323503, A323504 and A323507.
The value of a(n) is computed from the binary expansion of n as follows: Starting from the least significant end of the binary expansion of n (A007088), we record the successive run lengths, subtract one from all lengths except the first one, and use the reversed partial sums of these adjusted values as the exponents of successive primes.
For 11, which is "1011" in base 2, we have run lengths [2, 1, 1] when scanned from the right, and when one is subtracted from all except the first, we have [2, 0, 0], partial sums of which is [2, 2, 2], which stays same when reversed, thus a(11) = 2^2 * 3^2 * 5^2 = 900.
For 13, which is "1101" in base 2, we have run lengths [1, 1, 2] when scanned from the right, and when one is subtracted from all except the first, we have [1, 0, 1], partial sums of which is [1, 1, 2], reversed [2, 1, 1], thus a(13) = 2^2 * 3^1 * 5^1 = 60.
Sequence A227183 is based on the same algorithm.
		

Crossrefs

Cf. A000079 (right edge), A000400 (left edge, apart from 2), A005811, A046523, A101296, A227183, A322585, A322825, A323503, A323504, A323507.
Other rearrangements of A025487 include A036035, A059901, A063008, A077569, A085988, A086141, A087443, A108951, A181821, A181822.
Cf. A005940, A283477, A323505 for other similar trees.

Programs

  • Mathematica
    {1}~Join~Array[Times @@ MapIndexed[Prime[First@ #2]^#1 &, Reverse@ Accumulate@ MapIndexed[Length[#1] - Boole[First@ #2 > 1] &, Split@ Reverse@ IntegerDigits[#, 2]]] &, 54] (* Michael De Vlieger, Feb 05 2020 *)
  • PARI
    A322827(n) = if(!n,1,my(bits = Vecrev(binary(n)), rl=1, o = List([])); for(i=2,#bits,if(bits[i]==bits[i-1], rl++, listput(o,rl))); listput(o,rl); my(es=Vecrev(Vec(o)), m=1); for(i=1,#es,m *= prime(i)^es[i]); (m));

Formula

a(n) = A046523(a(n)) = A046523(A322825(n)).
A001221(a(n)) = A005811(n).
A001222(a(n)) = A227183(n).
A322585(a(n)) = 1.

A008567 Digits of powers of 6.

Original entry on oeis.org

1, 6, 3, 6, 2, 1, 6, 1, 2, 9, 6, 7, 7, 7, 6, 4, 6, 6, 5, 6, 2, 7, 9, 9, 3, 6, 1, 6, 7, 9, 6, 1, 6, 1, 0, 0, 7, 7, 6, 9, 6, 6, 0, 4, 6, 6, 1, 7, 6, 3, 6, 2, 7, 9, 7, 0, 5, 6, 2, 1, 7, 6, 7, 8, 2, 3, 3, 6, 1, 3, 0, 6, 0, 6, 9, 4, 0, 1, 6, 7, 8, 3, 6, 4, 1, 6, 4, 0, 9, 6, 4, 7, 0, 1, 8, 4, 9, 8, 4
Offset: 0

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Author

Keywords

Comments

Irregular table with row length sequence A210436. - Jason Kimberley, Nov 26 2012
The constant whose decimal expansion is this sequence is irrational (Mahler, 1981). - Amiram Eldar, Mar 23 2025

Examples

			Triangle begins:
  1;
  6;
  3, 6;
  2, 1, 6;
  1, 2, 9, 6;
  7, 7, 7, 6;
  4, 6, 6, 5, 6;
  2, 7, 9, 9, 3, 6;
  1, 6, 7, 9, 6, 1, 6;
  1, 0, 0, 7, 7, 6, 9, 6;
  ...
		

Crossrefs

A009992 Powers of 48: a(n) = 48^n.

Original entry on oeis.org

1, 48, 2304, 110592, 5308416, 254803968, 12230590464, 587068342272, 28179280429056, 1352605460594688, 64925062108545024, 3116402981210161152, 149587343098087735296, 7180192468708211294208, 344649238497994142121984, 16543163447903718821855232
Offset: 0

Views

Author

Keywords

Comments

Same as Pisot sequences E(1, 48), L(1, 48), P(1, 48), T(1, 48). Essentially same as Pisot sequences E(48, 2304), L(48, 2304), P(48, 2304), T(48, 2304). See A008776 for definitions of Pisot sequences.
If X_1, X_2, ..., X_n is a partition of the set {1,2,...,2*n} into blocks of size 2 then, for n>=1, a(n) is equal to the number of functions f : {1,2,..., 2*n}->{1,2,3,4,5,6,7} such that for fixed y_1,y_2,...,y_n in {1,2,3,4,5,6,7} we have f(X_i)<>{y_i}, (i=1,2,...,n). - Milan Janjic, May 24 2007
The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n >= 1, a(n) equals the number of 48-colored compositions of n such that no adjacent parts have the same color. - Milan Janjic, Nov 17 2011

Crossrefs

Cf. A001018 (powers of 8), ..., A001029 (powers of 19), A009964 (powers of 20), ..., A009991 (powers of 47), A087752 (powers of 49).
Cf. A000079 (2^n), A000244 (3^n), A000302 (4^n), A000400 (6^n), A001018 (8^n), A001021 (12^n), A001025 (16^n), A009968 (24^n).

Programs

Formula

G.f.: 1/(1-48*x). - Philippe Deléham, Nov 24 2008
a(n) = 48^n; a(n) = 48*a(n-1), a(0)=1. - Vincenzo Librandi, Nov 21 2010
E.g.f.: exp(48*x). - Muniru A Asiru, Nov 21 2018

Extensions

Edited by M. F. Hasler, Apr 19 2015

A038221 Triangle whose (i,j)-th entry is binomial(i,j)*3^(i-j)*3^j.

Original entry on oeis.org

1, 3, 3, 9, 18, 9, 27, 81, 81, 27, 81, 324, 486, 324, 81, 243, 1215, 2430, 2430, 1215, 243, 729, 4374, 10935, 14580, 10935, 4374, 729, 2187, 15309, 45927, 76545, 76545, 45927, 15309, 2187, 6561, 52488, 183708, 367416, 459270, 367416, 183708, 52488, 6561
Offset: 0

Views

Author

Keywords

Comments

Triangle of coefficients in expansion of (3 + 3x)^n = 3^n (1 +x)^n, where n is a nonnegative integer. (Coefficients in expansion of (1 +x)^n are given in A007318: Pascal's triangle). - Zagros Lalo, Jul 23 2018

Examples

			Triangle begins as:
     1;
     3,     3;
     9,    18,      9;
    27,    81,     81,     27;
    81,   324,    486,    324,     81;
   243,  1215,   2430,   2430,   1215,    243;
   729,  4374,  10935,  14580,  10935,   4374,    729;
  2187, 15309,  45927,  76545,  76545,  45927,  15309,  2187;
  6561, 52488, 183708, 367416, 459270, 367416, 183708, 52488, 6561;
		

References

  • Shara Lalo and Zagros Lalo, Polynomial Expansion Theorems and Number Triangles, Zana Publishing, 2018, ISBN: 978-1-9995914-0-3, pp. 44, 48

Crossrefs

Columns k: A000244 (k=0), 3*A027471 (k=1), 3^2*A027472 (k=2), 3^3*A036216 (k=3), 3^4*A036217 (k=4), 3^5*A036219 (k=5), 3^6*A036220 (k=6), 3^7*A036221 (k=7), 3^8*A036222 (k=8), 3^9*A036223 (k=9), 3^10*A172362 (k=10).

Programs

  • GAP
    Flat(List([0..8],i->List([0..i],j->Binomial(i,j)*3^(i-j)*3^j))); # Muniru A Asiru, Jul 23 2018
    
  • Haskell
    a038221 n = a038221_list !! n
    a038221_list = concat $ iterate ([3,3] *) [1]
    instance Num a => Num [a] where
       fromInteger k = [fromInteger k]
       (p:ps) + (q:qs) = p + q : ps + qs
       ps + qs         = ps ++ qs
       (p:ps) * qs'@(q:qs) = p * q : ps * qs' + [p] * qs
        *                = []
    -- Reinhard Zumkeller, Apr 02 2011
    
  • Magma
    [3^n*Binomial(n,k): k in [0..n], n in [0..10]]; // G. C. Greubel, Oct 17 2022
    
  • Mathematica
    (* programs from Zagros Lalo, Jul 23 2018 *)
    t[0, 0]=1; t[n_, k_]:= t[n, k]= If[n<0 || k<0, 0, 3 t[n-1, k] + 3 t[n-1, k-1]]; Table[t[n, k], {n,0,10}, {k,0,n}]//Flatten
    Table[CoefficientList[Expand[3^n *(1+x)^n], x], {n,0,10}]//Flatten
    Table[3^n Binomial[n, k], {n,0,10}, {k,0,n}]//Flatten  (* End *)
  • SageMath
    def A038221(n,k): return 3^n*binomial(n,k)
    flatten([[A038221(n,k) for k in range(n+1)] for n in range(10)]) # G. C. Greubel, Oct 17 2022

Formula

G.f.: 1/(1 - 3*x - 3*x*y). - Ilya Gutkovskiy, Apr 21 2017
T(0,0) = 1; T(n,k) = 3 T(n-1,k) + 3 T(n-1,k-1) for k = 0...n; T(n,k)=0 for n or k < 0. - Zagros Lalo, Jul 23 2018
From G. C. Greubel, Oct 17 2022: (Start)
T(n, k) = T(n, n-k).
T(n, n) = A000244(n).
T(n, n-1) = 3*A027471(n).
T(n, n-2) = 9*A027472(n+1).
T(n, n-3) = 27*A036216(n-3).
T(n, n-4) = 81*A036217(n-4).
T(n, n-5) = 243*A036219(n-5).
Sum_{k=0..n} T(n, k) = A000400(n).
Sum_{k=0..n} (-1)^k * T(n, k) = A000007(n).
Sum_{k=0..floor(n/2)} T(n-k, k) = A030195(n+1), n >= 0.
Sum_{k=0..floor(n/2)} (-1)^k * T(n-k, k) = A057083(n).
T(n, k) = 3^k * A027465(n, k). (End)

A067411 Third column of triangle A067410 and second column of A067417.

Original entry on oeis.org

1, 4, 24, 144, 864, 5184, 31104, 186624, 1119744, 6718464, 40310784, 241864704, 1451188224, 8707129344, 52242776064, 313456656384, 1880739938304, 11284439629824, 67706637778944, 406239826673664
Offset: 0

Views

Author

Wolfdieter Lang, Jan 25 2002

Keywords

Comments

Let f(k) be the sum of the smallest three positive divisors of k, g(k) be the sum of the largest two positive divisors of k, this sequence from a(2) onwards contains the numbers k for which g(k) is a positive integer power of f(k). - Yifan Xie, Jan 27 2024

Crossrefs

A002001, A067412 (second and fourth column of A067410), A000244, A067403 (first and third column of A067417), A000400 (powers of 6).
Row sums of A038195.

Programs

  • Mathematica
    CoefficientList[Series[(1-2x)/(1-6x),{x,0,30}],x] (* Harvey P. Dale, Feb 26 2015 *)
  • PARI
    a(n) = if(n<=0, 0, 4*6^(n-1) ); \\ Joerg Arndt, Feb 23 2014

Formula

a(n) = A067410(n+2, 2) = A067417(n+1, 1).
a(n) = 4 * 6^(n-1), for n >= 1, a(0)=1.
G.f.: (1-2*x)/(1-6*x).
E.g.f.: (2*exp(6*x)+1) / 3 = exp(3*x)*(cosh(3*x) + sinh(3*x)/3). - Paul Barry, Nov 20 2003
a(n) = Sum_{k=0..n} C(n,k) * A001045(n+k+1). - Paul Barry, Apr 19 2010

Extensions

Incorrect formula deleted by Harvey P. Dale, Feb 26 2015
Formula restored by Sean A. Irvine, Jan 10 2021

A223269 T(n,k)=Rolling cube face footprints: number of nXk 0..5 arrays starting with 0 where 0..5 label faces of a cube and every array movement to a horizontal, diagonal or antidiagonal neighbor moves across a corresponding cube edge.

Original entry on oeis.org

1, 4, 6, 16, 48, 36, 64, 576, 576, 216, 256, 6144, 20992, 6912, 1296, 1024, 67584, 622592, 765952, 82944, 7776, 4096, 737280, 19726336, 63438848, 27951104, 995328, 46656, 16384, 8060928, 611319808, 5889851392, 6467616768, 1020002304, 11943936
Offset: 1

Views

Author

R. H. Hardin Mar 19 2013

Keywords

Comments

Table starts
....1......4.........16...........64.............256...............1024
....6.....48........576.........6144...........67584.............737280
...36....576......20992.......622592........19726336..........611319808
..216...6912.....765952.....63438848......5889851392.......522106961920
.1296..82944...27951104...6467616768...1771674009600....450204914417664
.7776.995328.1020002304.659411697664.534392715870208.389343801904201728

Examples

			Some solutions for n=3 k=4
..0..3..1..2....0..1..0..1....0..4..5..1....0..4..2..4....0..2..1..3
..0..2..4..3....0..3..5..1....0..4..0..3....0..1..0..4....0..3..4..2
..4..2..1..2....0..2..0..1....3..1..5..4....3..4..0..1....0..3..4..0
Face neighbors:
0.->.1.2.3.4
1.->.0.2.3.5
2.->.0.1.4.5
3.->.0.1.4.5
4.->.0.3.2.5
5.->.1.3.4.2
		

Crossrefs

Column 1 is A000400(n-1)
Column 2 is 4*12^(n-1)
Column 3 is A223197
Row 1 is A000302(n-1)

Formula

Empirical for column k:
k=1: a(n) = 6*a(n-1)
k=2: a(n) = 12*a(n-1)
k=3: a(n) = 40*a(n-1) -128*a(n-2)
k=4: a(n) = 112*a(n-1) -1024*a(n-2)
k=5: [order 6]
k=6: [order 9]
k=7: [order 19]
Empirical for row n:
n=1: a(n) = 4*a(n-1)
n=2: a(n) = 8*a(n-1) +32*a(n-2)
n=3: a(n) = 24*a(n-1) +256*a(n-2) -1024*a(n-3) for n>4
n=4: [order 6] for n>7
n=5: [order 10] for n>11
n=6: [order 23] for n>24

A223556 T(n,k)=Petersen graph (3,1) coloring a rectangular array: number of nXk 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,3 3,5 3,4 1,2 1,4 4,5 2,0 2,5 and every array movement to a horizontal or antidiagonal neighbor moves along an edge of this graph, with the array starting at 0.

Original entry on oeis.org

1, 3, 6, 9, 27, 36, 27, 171, 243, 216, 81, 1089, 3249, 2187, 1296, 243, 6939, 44217, 61731, 19683, 7776, 729, 44217, 609309, 1795473, 1172889, 177147, 46656, 2187, 281763, 8410671, 53599905, 72906921, 22284891, 1594323, 279936, 6561, 1795473
Offset: 1

Views

Author

R. H. Hardin Mar 22 2013

Keywords

Comments

Table starts
........1..........3.............9...............27...................81
........6.........27...........171.............1089.................6939
.......36........243..........3249............44217...............609309
......216.......2187.........61731..........1795473.............53599905
.....1296......19683.......1172889.........72906921...........4715559621
.....7776.....177147......22284891.......2960456193.........414863325945
....46656....1594323.....423412929.....120212193177.......36498667573629
...279936...14348907....8044845651....4881332621169.....3211064180380305
..1679616..129140163..152852067369..198211242377097...282501632829717621
.10077696.1162261467.2904189280011.8048559615522273.24853807982558115945

Examples

			Some solutions for n=3 k=4
..0..3..5..2....0..1..4..1....0..2..5..2....0..2..5..2....0..1..2..0
..5..3..0..1....0..1..0..3....1..2..5..2....5..2..1..4....2..0..1..2
..4..3..4..3....2..1..4..5....0..2..0..1....1..2..1..2....1..4..5..3
		

Crossrefs

Column 1 is A000400(n-1)
Column 2 is A013708(n-1)
Column 3 = 9*19^(n-1) is row 8 of A223556 with T(2+,3) = A121057(8,1+)
Row 1 is A000244(n-1)

Formula

Empirical for column k:
k=1: a(n) = 6*a(n-1)
k=2: a(n) = 9*a(n-1)
k=3: a(n) = 19*a(n-1)
k=4: a(n) = 41*a(n-1) -16*a(n-2)
k=5: a(n) = 95*a(n-1) -626*a(n-2) +720*a(n-3) for n>4
k=6: [order 8] for n>9
k=7: [order 13] for n>15
Empirical for row n:
n=1: a(n) = 3*a(n-1)
n=2: a(n) = 7*a(n-1) -4*a(n-2) for n>3
n=3: a(n) = 17*a(n-1) -47*a(n-2) +41*a(n-3) -10*a(n-4) for n>6
n=4: [order 13] for n>16
n=5: [order 41] for n>45

A224012 T(n,k)=Number of nXk 0..2 arrays with rows nondecreasing and antidiagonals unimodal.

Original entry on oeis.org

3, 6, 9, 10, 36, 27, 15, 100, 216, 81, 21, 225, 868, 1296, 243, 28, 441, 2661, 7378, 7776, 729, 36, 784, 6815, 28541, 62764, 46656, 2187, 45, 1296, 15340, 90051, 297859, 534352, 279936, 6561, 55, 2025, 31324, 245055, 1108969, 3094127, 4549684, 1679616
Offset: 1

Views

Author

R. H. Hardin Mar 30 2013

Keywords

Comments

Table starts
.....3........6.........10..........15...........21............28............36
.....9.......36........100.........225..........441...........784..........1296
....27......216........868........2661.........6815.........15340.........31324
....81.....1296.......7378.......28541........90051........245055........595822
...243.....7776......62764......297859......1108969.......3516324.......9866389
...729....46656.....534352.....3094127.....13275381......47735665.....150787422
..2187...279936....4549684....32148473....157347899.....630339756....2200064042
..6561..1679616...38737252...334179881...1859567103....8213689391...31256208954
.19683.10077696..329817976..3474343713..21962353421..106375878027..437370837827
.59049.60466176.2808146488.36122604265.259365424097.1373916879120.6067995150599

Examples

			Some solutions for n=3 k=4
..1..1..2..2....0..1..1..1....0..0..0..0....0..0..0..1....0..2..2..2
..0..2..2..2....0..1..1..1....0..1..2..2....2..2..2..2....0..0..1..1
..1..1..2..2....0..2..2..2....1..2..2..2....2..2..2..2....0..0..2..2
		

Crossrefs

Column 1 is A000244
Column 2 is A000400
Row 1 is A000217(n+1)
Row 2 is A000537(n+1)

Formula

Empirical: columns k=1..7 have recurrences of order 1,1,5,7,11,14,19
Empirical: rows n=1..7 are polynomials of degree 2*n for k>0,0,1,2,3,4,5
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