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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A287817 Number of nonary sequences of length n such that no two consecutive terms have distance 2.

Original entry on oeis.org

1, 9, 67, 501, 3747, 28025, 209609, 1567743, 11725731, 87701095, 655949055, 4906086571, 36694443381, 274451368893, 2052723708275, 15353082914309, 114831408642039, 858866749063989, 6423783365292409, 48045861327359751, 359352839194448551, 2687733333725785179
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Examples

			For n=2 the a(2) = 81 - 14 = 67 sequences contain every combination except these fourteen: 02,20,13,31,24,42,35,53,46,64,57,75,68,86.

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819.

Programs

  • Mathematica
    LinearRecurrence[{8, -1, -23, 10, 1}, {1, 9, 67 , 501, 3747}, 40]
  • Python
    def a(n):
 if n in [0, 1, 2, 3, 4]:
  return [1, 9, 67 , 501, 3747][n]
 return 8*a(n-1)-a(n-2)-23*a(n-3)+10*a(n-4)+a(n-5)

Formula

a(n) = 8*a(n-1) - 1*a(n-2) - 23*a(n-3) + 10*a(n-4) + a(n-5), a(0)=1, a(1)=9, a(2)=67, a(3)=501, a(4)=3747.
G.f: (-1 - x + 4 x^2 + 3 x^3 - 3 x^4)/(-1 + 8 x - x^2 - 23 x^3 + 10 x^4 + x^5).

A287818 Number of nonary sequences of length n such that no two consecutive terms have distance 3.

Original entry on oeis.org

1, 9, 69, 531, 4089, 31491, 242529, 1867851, 14385369, 110789811, 853254609, 6571393371, 50609994249, 389776014531, 3001884188289, 23119197549291, 178053936060729, 1371293449053651, 10561101680875569, 81336980637343611, 626421808927336809, 4824426473972595171
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Examples

			For n=2 the a(2) = 81 - 12 = 69 sequences contain every combination except these twelve: 03,30,14,41,25,52,36,63,47,74,58,85.

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819.

Programs

  • Mathematica
    LinearRecurrence[{9, -10}, {1, 9, 69}, 40]
  • Python
    def a(n):
 if n in [0, 1, 2]:
  return [1, 9, 69][n]
 return 9*a(n-1)-10*a(n-2)

Formula

For n>2, a(n) = 9*a(n-1) - 10*a(n-2), a(0)=1, a(1)=9, a(2)=69.
G.f.: (1 - 2 x^2)/(1 - 9 x + 10 x^2).
For n>0, a(n)=(1/5)(3 - 18/sqrt(41))*((9 - sqrt(41))/2)^n + (1/5)(3 + 18/sqrt(41))*((9 + sqrt(41))/2)^n.
a(n) = A178869(n+1)-2*A178869(n-1). - R. J. Mathar, Oct 20 2019

A287826 Number of sequences over the alphabet {0,1,...,9} such that no two consecutive terms have distance 2.

Original entry on oeis.org

1, 10, 84, 708, 5968, 50308, 424080, 3574860, 30134944, 254028100, 2141377008, 18051134892, 152165391616, 1282706408548, 10812811724688, 91148603152524, 768354066287200, 6476983198439812, 54598931916359472, 460251829451302764, 3879778213203474880
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287831.

Programs

  • Mathematica
    LinearRecurrence[{10, -13, -2}, {1, 10, 84}, 40]
  • Python
    def a(n):
 if n in [0, 1, 2]:
  return [1, 10, 84][n]
 return 10*a(n-1)-13*a(n-2)-2*a(n-3)

Formula

a(n) = 10*a(n-1) - 13*a(n-2) - 2a(n-3), a(0)=1, a(1)=10, a(2)=84.
G.f.: (1 - 3 x^2)/(1 - 10 x + 13 x^2 + 2 x^3).

A287827 Number of sequences over the alphabet {0,1,...,9} such that no two consecutive terms have distance 3.

Original entry on oeis.org

1, 10, 86, 742, 6404, 55274, 477082, 4117804, 35541714, 306768722, 2647791524, 22853698754, 197255539962, 1702558017644, 14695170558994, 126837403201602, 1094762853302164, 9449150445514434, 81557794797885642, 703944119701429084, 6075903902137709074
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287831.

Programs

  • Mathematica
    LinearRecurrence[{9, -1, -20, 10}, {1, 10, 86, 742, 6404}, 30]
  • Python
    def a(n):
 if n in [0, 1, 2, 3, 4]:
  return [1, 10, 86, 742, 6404][n]
 return 9*a(n-1)-a(n-2)-20*a(n-3)+10*a(n-4)

Formula

For n>4, a(n) = 9*a(n-1) - a(n-2) - 20*a(n-3) + 10*a(n-4), a(0)=1, a(1)=10, a(2)=86, a(3)=742, a(4)=6404.
G.f.: (-1 - x + 3*x^2 + 2*x^3 - 2*x^4)/(-1 + 9*x - x^2 - 20*x^3 + 10*x^4).

A287828 Number of sequences over the alphabet {0,1,...,9} such that no two consecutive terms have distance 4.

Original entry on oeis.org

1, 10, 88, 776, 6844, 60364, 532412, 4695892, 41417932, 365307620, 3222026092, 28418383780, 250651147340, 2210751960772, 19498910274028, 171981076403492, 1516879160180620, 13378927697789188, 118002614210453804, 1040787219651555556, 9179779989094951372
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287831.

Programs

  • Mathematica
    LinearRecurrence[{9, 0, -14}, {1, 10, 88, 776}, 30]
  • Python
    def a(n):
 if n in [0, 1, 2, 3]:
  return [1, 10, 88, 776][n]
 return 9*a(n-1)-14*a(n-3)

Formula

For n>3, a(n) = 9*a(n-1) - 14*a(n-3), a(0)=1, a(1)=10, a(2)=88, a(3)=776.
G.f.: (1 + x - 2*x^2 - 2*x^3)/(1 - 9*x + 14*x^3).

A287829 Number of sequences over the alphabet {0,1,...,9} such that no two consecutive terms have distance 6.

Original entry on oeis.org

1, 10, 92, 848, 7816, 72040, 663992, 6120008, 56408056, 519912520, 4792028792, 44168084168, 407096815096, 3752207504200, 34584061167992, 318760965520328, 2938016812018936, 27079673239211080, 249593092776937592, 2300497181470860488, 21203660818791619576
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Comments

In general, the number of sequences over the alphabet {0,1,...,9} such that no two consecutive terms have distance 5+k for k in {0,1,2,3,4} is given by a(n) = 9*a(n-1) + 2*k*a(n-2), a(0)=1, a(1)=10.

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287831.

Programs

  • Mathematica
    LinearRecurrence[{9, 2}, {1, 10}, 30]
  • Python
    def a(n):
 if n in [0, 1]:
  return [1, 10][n]
 return 9*a(n-1)+2*a(n-2)

Formula

a(n) = 9*a(n-1) + 2*a(n-2), a(0)=1, a(1)=10.
G.f.: (-1 - x)/(-1 + 9*x + 2*x^2).
a(n) = ((1 - 11/sqrt(89))/2)*((9 - sqrt(89))/2)^n + ((1 + 11/sqrt(89))/2)*((9 + sqrt(89))/2)^n.
a(n) = A015579(n)+A015579(n+1). - R. J. Mathar, Oct 20 2019

A287830 Number of sequences over the alphabet {0,1,...,9} such that no two consecutive terms have distance 7.

Original entry on oeis.org

1, 10, 94, 886, 8350, 78694, 741646, 6989590, 65872894, 620814406, 5850821230, 55140648694, 519669123166, 4897584703270, 46156938822094, 435002788211926, 4099652849195710, 38636886795609094, 364130592557264686, 3431722880197818550, 32342028292009425694
Offset: 0

Views

Author

David Nacin, Jun 02 2017

Keywords

Comments

In general, the number of sequences over the alphabet {0,1,...,9} such that no two consecutive terms have distance 5+k for k in {0,1,2,3,4} is given by a(n) = 9*a(n-1) + 2*k*a(n-2), a(0)=1, a(1)=10.

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287831.

Programs

  • Mathematica
    LinearRecurrence[{9, 4}, {1, 10}, 30]
  • Python
    def a(n):
 if n in [0, 1]:
  return [1, 10][n]
 return 9*a(n-1)+4*a(n-2)

Formula

a(n) = 9*a(n-1) + 4*a(n-2), a(0)=1, a(1)=10.
G.f.: (-1 - x)/(-1 + 9*x + 4*x^2).
a(n) = ((1 - 11/sqrt(97))/2)*((9 - sqrt(97))/2)^n + ((1 + 11/sqrt(97))/2)*((9 + sqrt(97))/2)^n.
a(n) = A015580(n)+A015580(n+1). - R. J. Mathar, Oct 20 2019

A287832 Number of words of length n over the alphabet {0,1,...,10} such that no two consecutive terms have distance 1.

Original entry on oeis.org

1, 11, 101, 929, 8545, 78599, 722973, 6650087, 61169169, 562649373, 5175390189, 47604538285, 437878494689, 4027716327495, 37047945974857, 340776308298291, 3134546038698889, 28832341420057365, 265207115001514409, 2439441626426418609, 22438596523731989473
Offset: 0

Views

Author

David Nacin, Jun 07 2017

Keywords

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287839.

Programs

  • Mathematica
    LinearRecurrence[{11, -14, -28, 39, 9, -10}, {1, 11, 101, 929, 8545, 78599, 722973}, 20]
  • Python
    def a(n):
 if n in [0,1,2,3,4,5,6]:
  return [1, 11, 101, 929, 8545, 78599, 722973][n]
 return 11*a(n-1) - 14*a(n-2) - 28*a(n-3) + 39*a(n-4) + 9*a(n-5) - 10*a(n-6)

Formula

For n>6, a(n) = 11*a(n-1) - 14*a(n-2) - 28*a(n-3) + 39*a(n-4) + 9*a(n-5) - 10*a(n-6), a(0)=1, a(1)=11, a(2)=101, a(3)=929, a(4)=8545, a(5)=78599, a(6)=722973.
G.f.: (1 - 6*x^2 + 9*x^4 - 2*x^6)/(1 - 11*x + 14*x^2 + 28*x^3 - 39*x^4 - 9*x^5 + 10*x^6).

A287833 Number of words of length n over the alphabet {0,1,...,10} such that no two consecutive terms have distance 2.

Original entry on oeis.org

1, 11, 103, 967, 9079, 85243, 800351, 7514541, 70554457, 662439857, 6219685951, 58396989455, 548292695881, 5147951686649, 48334414751849, 453814602701801, 4260891430727991, 40005754941255473, 375616336261903907, 3526683405274793053, 33112233522155404139
Offset: 0

Views

Author

David Nacin, Jun 07 2017

Keywords

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287839.

Programs

  • Mathematica
    LinearRecurrence[{10, -2, -37, 16, 19, 1}, {1, 11, 103, 967, 9079, 85243}, 20]
  • Python
    def a(n):
 if n in [0,1,2,3,4,5]:
  return [1, 11, 103, 967, 9079, 85243][n]
 return 10*a(n-1) - 2*a(n-2) - 37*a(n-3) + 16*a(n-4) + 19*a(n-5) + a(n-6)

Formula

a(n) = 10*a(n-1) - 2*a(n-2) - 37*a(n-3) + 16*a(n-4) + 19*a(n-5) + a(n-6), a(0)=1, a(1)=11, a(2)=103, a(3)=967, a(4)=9079, a(5)=85243.
G.f.: (-1 - x + 5*x^2 + 4*x^3 - 6*x^4 - 3*x^5)/(-1 + 10*x - 2*x^2 - 37*x^3 + 16*x^4 + 19*x^5 + x^6).

A287834 Number of words of length n over the alphabet {0,1,...,10} such that no two consecutive terms have distance 3.

Original entry on oeis.org

1, 11, 105, 1005, 9621, 92105, 881753, 8441329, 80811789, 773639469, 7406320733, 70903294113, 678781988705, 6498216958121, 62209699634757, 595555173609653, 5701457600593525, 54582044135967257, 522532964509030377, 5002390498942001761, 47889630709552579709
Offset: 0

Views

Author

David Nacin, Jun 07 2017

Keywords

Links

Crossrefs

Cf. A040000, A003945, A083318, A078057, A003946, A126358, A003946, A055099, A003947, A015448, A126473. A287804-A287819. A287825-A287839.

Programs

  • Mathematica
    LinearRecurrence[{10, -2, -21, 10}, {1, 11, 105, 1005, 9621}, 20]
  • Python
    def a(n):
 if n in [0,1,2,3,4]:
  return [1, 11, 105, 1005, 9621][n]
 return 10*a(n-1) - 2*a(n-2) - 21*a(n-3) + 10*a(n-4)

Formula

a(n) = 10*a(n-1) - 2*a(n-2) - 21*a(n-3) + 10*a(n-4), a(0)=1, a(1)=11, a(2)=105, a(3)=1005, a(4)=9621.
G.f.: (-1 - x + 3*x^2 + 2*x^3 - 2*x^4)/(-1 + 10*x - 2*x^2 - 21*x^3 + 10*x^4).
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