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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A218737 a(n) = (34^n - 1)/33.

Original entry on oeis.org

0, 1, 35, 1191, 40495, 1376831, 46812255, 1591616671, 54114966815, 1839908871711, 62556901638175, 2126934655697951, 72315778293730335, 2458736461986831391, 83597039707552267295, 2842299350056777088031, 96638177901930420993055, 3285698048665634313763871
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 34 (A009978).

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1 - x)*(1 - 34*x)).
a(n) = 35*a(n-1) - 34*a(n-2).
a(n) = floor(34^n/33). (End)
E.g.f.: exp(x)*(exp(33*x) - 1)/33. - Stefano Spezia, Mar 26 2023

A218738 a(n) = (35^n - 1)/34.

Original entry on oeis.org

0, 1, 36, 1261, 44136, 1544761, 54066636, 1892332261, 66231629136, 2318107019761, 81133745691636, 2839681099207261, 99388838472254136, 3478609346528894761, 121751327128511316636, 4261296449497896082261, 149145375732426362879136, 5220088150634922700769761
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 35 (A009979).

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1 - x)*(1 - 35*x)).
a(n) = 36*a(n-1) - 35*a(n-2).
a(n) = floor(35^n/34). (End)
E.g.f.: exp(x)*(exp(34*x) - 1)/34. - Stefano Spezia, Mar 28 2023

A218745 a(n) = (42^n - 1)/41.

Original entry on oeis.org

0, 1, 43, 1807, 75895, 3187591, 133878823, 5622910567, 236162243815, 9918814240231, 416590198089703, 17496788319767527, 734865109430236135, 30864334596069917671, 1296302053034936542183, 54444686227467334771687, 2286676821553628060410855, 96040426505252378537255911
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 42 (A009986).

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1-x)*(1-42*x)).
a(n) = 43*a(n-1) - 42*a(n-2).
a(n) = floor(42^n/41). (End)
E.g.f.: exp(x)*(exp(41*x) - 1)/41. - Elmo R. Oliveira, Aug 29 2024

A261544 a(n) = Sum_{k=0..n} 1000^k.

Original entry on oeis.org

1, 1001, 1001001, 1001001001, 1001001001001, 1001001001001001, 1001001001001001001, 1001001001001001001001, 1001001001001001001001001, 1001001001001001001001001001, 1001001001001001001001001001001, 1001001001001001001001001001001001
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 24 2015

Keywords

Comments

A sequence of palindromic numbers.

Examples

			From _Bruno Berselli_, Aug 25 2015: (Start)
a(n)   is the binary representation of    A023001
-------------------------------------------------
1  ...........................................  1
1001  ........................................  9
1001001 .....................................  73
1001001001  ................................  585
1001001001001  ............................  4681
1001001001001001  ........................  37449
1001001001001001001  ....................  299593
1001001001001001001001  ................  2396745
1001001001001001001001001  ............  19173961, etc.
(End)
		

Crossrefs

Subsequence of A033146.
Sums of 100^k: A094028; sums of 10^k: A000042.
Cf. similar sequences of the form (k^n-1)/(k-1) listed in A269025.

Programs

  • Magma
    [(1000^(n+1)-1)/999: n in [0..30]]; // Vincenzo Librandi, Aug 24 2015
  • Mathematica
    Table[(1000^(n + 1) - 1)/999, {n, 0, 15}]
    LinearRecurrence[{1001, -1000}, {1, 1001}, 20] (* Vincenzo Librandi, Aug 24 2015 *)
  • PARI
    Vec(1 / ((x-1)*(1000*x-1)) + O(x^20)) \\ Colin Barker, Aug 24 2015
    

Formula

a(n) = (1000^(n + 1) - 1)/999.
a(n) = 1001*a(n-1) - 1000*a(n-2). - Colin Barker, Aug 24 2015
G.f.: 1 / ((x-1)*(1000*x-1)). - Colin Barker, Aug 24 2015
E.g.f.: (1/999)*(1000000*exp(1000*x) - exp(x)). - G. C. Greubel, Aug 29 2015

A344822 Numbers m with decimal expansion (d_1, ..., d_k) such that d_i = m * i mod 10 for i = 1..k.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 505, 50505, 246802, 482604, 628406, 864208, 5050505, 505050505, 12345678901, 24680246802, 36925814703, 48260482604, 50505050505, 62840628406, 74185296307, 86420864208, 98765432109, 5050505050505, 505050505050505, 2468024680246802
Offset: 1

Views

Author

Rémy Sigrist, May 29 2021

Keywords

Comments

This sequence is infinite as it contains 5 * A094028(k) for any k > 0.
Also contains terms with patterns 2(46802)^k, 4(82604)^k, 6(28406)^k, 8(64208)^k, 1(2345678901)^k, 3(6925814703)^k, 7(4185296307)^k, 9(8765432109)^k for k >= 0, where ^ denotes repeated concatenation; all terms have first and last digits the same. - Michael S. Branicky, May 29 2021

Examples

			- 4 * 1 = 4 mod 10,
- 4 * 2 = 8 mod 10,
- 4 * 3 = 2 mod 10,
- 4 * 4 = 6 mod 10,
- 4 * 5 = 0 mod 10,
- 4 * 6 = 4 mod 10,
so 482604 is a term.
		

Crossrefs

Programs

  • PARI
    is(n) = { my (d=digits(n)); for (k=1, #d, if (d[k] != (n*k)%10, return (0))); return (1) }
    
  • PARI
    See Links section.
    
  • Python
    def ok(m):
      d = str(m)
      return all(d[i-1] == str((m*i)%10) for i in range(1, len(d)+1))
    print(list(filter(ok, range(10**6)))) # Michael S. Branicky, May 29 2021
    
  • Python
    def auptod(maxdigits):
      alst = [0]
      for k in range(1, maxdigits+1):
        for d1 in range(1, 10):
          d = [(d1*i)%10 for i in range(1, k+1)]
          if d1 == d[-1]: alst.append(int("".join(map(str, d))))
      return alst
    print(auptod(16)) # Michael S. Branicky, May 29 2021

A098610 a(n) = 10^n + (-1)^n.

Original entry on oeis.org

2, 9, 101, 999, 10001, 99999, 1000001, 9999999, 100000001, 999999999, 10000000001, 99999999999, 1000000000001, 9999999999999, 100000000000001, 999999999999999, 10000000000000001, 99999999999999999, 1000000000000000001, 9999999999999999999, 100000000000000000001
Offset: 0

Views

Author

Henry Bottomley, Sep 17 2004

Keywords

Crossrefs

Programs

  • Magma
    [10^n+(-1)^n: n in [0..20]]; // Vincenzo Librandi, Sep 23 2016
  • Mathematica
    Total/@Partition[Riffle[10^Range[0,20],{1,-1}],2] (* or *) Table[10^n+(-1)^n,{n,0,20}] (* Harvey P. Dale, Aug 20 2012 *)

Formula

a(n) = A098611(n) + 2*(-1)^n.
a(n) = A098609(n)/A098611(n).
a(n) = A098609(n)/(11*A015585(n)).
a(n) = 9*A094028(n+1)/A015585(n).
From Chai Wah Wu, Sep 22 2016: (Start)
a(n) = 9*a(n-1) + 10*a(n-2) for n > 1.
G.f.: (9*x - 2)/((x + 1)*(10*x - 1)). (End)
E.g.f.: exp(-x)*(exp(11*x) + 1). - Elmo R. Oliveira, Aug 17 2024

A218727 a(n) = (24^n - 1)/23.

Original entry on oeis.org

0, 1, 25, 601, 14425, 346201, 8308825, 199411801, 4785883225, 114861197401, 2756668737625, 66160049703001, 1587841192872025, 38108188628928601, 914596527094286425, 21950316650262874201, 526807599606308980825, 12643382390551415539801, 303441177373233972955225
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 24 (A009968); q-integers for q=24: diagonal k=1 in triangle A022188.
Partial sums are in A014913. Also, the sequence is related to A014942 by A014942(n) = n*a(n) - Sum_{i=0..n-1} a(i) for n > 0. [Bruno Berselli, Nov 07 2012]

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1-x)*(1-24*x)).
a(n) = floor(24^n/23).
a(n) = 25*a(n-1) - 24*a(n-2). (End)
E.g.f.: exp(x)*(exp(23*x) - 1)/23. - Elmo R. Oliveira, Aug 29 2024

A218729 a(n) = (26^n - 1)/25.

Original entry on oeis.org

0, 1, 27, 703, 18279, 475255, 12356631, 321272407, 8353082583, 217180147159, 5646683826135, 146813779479511, 3817158266467287, 99246114928149463, 2580398988131886039, 67090373691429037015, 1744349715977154962391, 45353092615406029022167, 1179180408000556754576343
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 26 (A009970); q-integers for q=26.

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1-x)*(1-26*x)).
a(n) = floor(26^n/25).
a(n) = 27*a(n-1) - 26*a(n-2). (End)
E.g.f.: exp(x)*(exp(25*x) - 1)/25. - Elmo R. Oliveira, Aug 29 2024

A218730 a(n) = (27^n - 1)/26.

Original entry on oeis.org

0, 1, 28, 757, 20440, 551881, 14900788, 402321277, 10862674480, 293292210961, 7918889695948, 213810021790597, 5772870588346120, 155867505885345241, 4208422658904321508, 113627411790416680717, 3067940118341250379360, 82834383195213760242721, 2236528346270771526553468
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 27 (A009971); q-integers for q=27.

Crossrefs

Programs

  • Magma
    [n le 2 select n-1 else 28*Self(n-1)-27*Self(n-2): n in [1..20]]; // Vincenzo Librandi, Nov 07 2012
    
  • Mathematica
    LinearRecurrence[{28, -27}, {0, 1}, 30] (* Vincenzo Librandi, Nov 07 2012 *)
  • Maxima
    A218730(n):=(27^n-1)/26$
    makelist(A218730(n),n,0,30); /* Martin Ettl, Nov 07 2012 */
  • PARI
    a(n)=27^n\26
    

Formula

G.f.: x/((1-x)*(1-27*x)). - Vincenzo Librandi, Nov 07 2012
a(n) = floor(27^n/26). - Vincenzo Librandi, Nov 07 2012
a(n) = 28*a(n-1) - 27*a(n-2). - Vincenzo Librandi, Nov 07 2012
E.g.f.: exp(14*x)*sinh(13*x)/13. - Elmo R. Oliveira, Aug 27 2024

A218731 a(n) = (28^n - 1)/27.

Original entry on oeis.org

0, 1, 29, 813, 22765, 637421, 17847789, 499738093, 13992666605, 391794664941, 10970250618349, 307167017313773, 8600676484785645, 240818941573998061, 6742930364071945709, 188802050194014479853, 5286457405432405435885, 148020807352107352204781, 4144582605859005861733869
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 28 (A009972).

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1-x)*(1-28*x)).
a(n) = floor(28^n/27).
a(n) = 29*a(n-1) - 28*a(n-2). (End)
E.g.f.: exp(x)*(exp(27*x) - 1)/27. - Elmo R. Oliveira, Aug 29 2024
Previous Showing 31-40 of 58 results. Next