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.

Showing 1-8 of 8 results.

A242329 a(n) = 5^n + 4.

Original entry on oeis.org

5, 9, 29, 129, 629, 3129, 15629, 78129, 390629, 1953129, 9765629, 48828129, 244140629, 1220703129, 6103515629, 30517578129, 152587890629, 762939453129, 3814697265629, 19073486328129, 95367431640629, 476837158203129, 2384185791015629, 11920928955078129
Offset: 0

Views

Author

Vincenzo Librandi, May 13 2014

Keywords

Comments

Subsequence of A226810. - Bruno Berselli, May 13 2014

Crossrefs

Cf. A000351, A003463, A034474, A132079, A178676, A226810, A242328, A253208 (similar sequence).

Programs

  • Magma
    [5^n+4: n in [0..30]];
  • Mathematica
    Table[5^n + 4, {n, 0, 30}]
    LinearRecurrence[{6,-5},{5,9},30] (* Harvey P. Dale, Mar 15 2025 *)

Formula

G.f.: (5-21*x)/((1-x)*(1-5*x)).
a(n) = 6*a(n-1) - 5*a(n-2) for n > 1.
From Elmo R. Oliveira, Dec 06 2023: (Start)
a(n) = A000351(n)+4 = A034474(n)+3 = A242328(n)+2.
a(n) = 5*a(n-1) - 16 with a(0) = 5.
E.g.f.: exp(5*x) + 4*exp(x). (End)

A327840 Numbers m that divide 4^m + 3.

Original entry on oeis.org

1, 7, 16387, 4509253, 24265177, 42673920001, 103949349763, 12939780075073
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Sep 27 2019

Keywords

Comments

Number of solutions < 10^9 to k^n == k-1 (mod n): 1 (if k = 1), 188 (if k = 2, see A006521), 5 (if k = 3, see A015973), 5 (if k = 4, see this sequence), 5 (if k = 5), 10 (if k = 6), 10 (if k = 7), 7 (if k = 8), 5 (if k = 9), 8 (if k = 10), 11 (if k = 11), 8 (if k = 12), 9 (if k = 13), 4 (if k = 14), 3 (if k = 15), 6 (if k = 16), 7 (if k = 17), 7 (if k = 18), ...
a(9) > 10^15. - Max Alekseyev, Nov 10 2022

Crossrefs

Solutions to k^n == 1-k (mod n): A006521 (k = 2), A015973 (k = 3), this sequence (k = 4), A123047 (k = 5), A327943 (k = 6).
Solutions to 4^n == k (mod n): A000079 (k = 0), A015950 (k = -1), A014945 (k = 1), A130421 (k = 2), this sequence (k = -3), A130422 (k = 3).

Programs

  • Magma
    [1] cat [n: n in [1..10^8] | Modexp(4,n,n) + 3 eq n];
    
  • Mathematica
    Select[Range[10^7], IntegerQ[(PowerMod[4, #, # ]+3)/# ]&] (* Metin Sariyar, Sep 28 2019 *)
  • PARI
    is(n)=Mod(4,n)^n==-3 \\ Charles R Greathouse IV, Sep 29 2019

Extensions

a(6)-a(7) from Giovanni Resta, Sep 29 2019
a(8) from Max Alekseyev, Nov 10 2022

A340666 A(n,k) is derived from n by replacing each 0 in its binary representation with a string of k 0's; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 2, 3, 0, 1, 4, 3, 1, 0, 1, 8, 3, 4, 3, 0, 1, 16, 3, 16, 5, 3, 0, 1, 32, 3, 64, 9, 6, 7, 0, 1, 64, 3, 256, 17, 12, 7, 1, 0, 1, 128, 3, 1024, 33, 24, 7, 8, 3, 0, 1, 256, 3, 4096, 65, 48, 7, 64, 9, 3, 0, 1, 512, 3, 16384, 129, 96, 7, 512, 33, 10, 7
Offset: 0

Views

Author

Alois P. Heinz, Jan 15 2021

Keywords

Examples

			Square array A(n,k) begins:
  0, 0,  0,   0,    0,     0,      0,       0,        0, ...
  1, 1,  1,   1,    1,     1,      1,       1,        1, ...
  1, 2,  4,   8,   16,    32,     64,     128,      256, ...
  3, 3,  3,   3,    3,     3,      3,       3,        3, ...
  1, 4, 16,  64,  256,  1024,   4096,   16384,    65536, ...
  3, 5,  9,  17,   33,    65,    129,     257,      513, ...
  3, 6, 12,  24,   48,    96,    192,     384,      768, ...
  7, 7,  7,   7,    7,     7,      7,       7,        7, ...
  1, 8, 64, 512, 4096, 32768, 262144, 2097152, 16777216, ...
  ...
		

Crossrefs

Columns k=0-2, 4 give: A038573, A001477, A084471, A084473.
Rows n=0..17, 19 give: A000004, A000012, A000079, A010701, A000302, A000051(k+1), A007283, A010727, A001018, A087289, A007582(k+1), A062709(k+2), A164346, A181565(k+1), A005009, A181404(k+3), A001025, A199493, A253208(k+1).
Main diagonal gives A340667.

Programs

  • Maple
    A:= (n, k)-> Bits[Join](subs(0=[0$k][], Bits[Split](n))):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
    # second Maple program:
    A:= proc(n, k) option remember; `if`(n<2, n,
         `if`(irem(n, 2, 'r')=1, A(r, k)*2+1, A(r, k)*2^k))
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    A[n_, k_] := FromDigits[IntegerDigits[n, 2] /. 0 -> Sequence @@ Table[0, {k}], 2];
    Table[A[n, d-n], {d, 0, 12}, {n, 0, d}] // Flatten (* Jean-François Alcover, Feb 02 2021 *)

Formula

A000120(A(n,k)) = A000120(n) = log_2(A(n,0)+1).
A023416(A(n,k)) = k * A023416(n) for n >= 1.

A253211 a(n) = 8^n + 7.

Original entry on oeis.org

8, 15, 71, 519, 4103, 32775, 262151, 2097159, 16777223, 134217735, 1073741831, 8589934599, 68719476743, 549755813895, 4398046511111, 35184372088839, 281474976710663, 2251799813685255, 18014398509481991, 144115188075855879, 1152921504606846983
Offset: 0

Views

Author

Vincenzo Librandi, Dec 30 2014

Keywords

Comments

Subsequence of A226825.

Crossrefs

Cf. similar sequences listed in A253208.

Programs

  • Magma
    [8^n+7: n in [0..30]];
  • Mathematica
    Table[8^n + 7, {n, 0, 40}]
    8^Range[0,20]+7 (* or *) LinearRecurrence[{9,-8},{8,15},30] (* Harvey P. Dale, Feb 25 2024 *)

Formula

G.f.: (8 - 57*x)/((1 - x)*(1 - 8*x)).
a(n) = 9*a(n-1) - 8*a(n-2) for n>1.

A253213 a(n) = 10^n + 9.

Original entry on oeis.org

10, 19, 109, 1009, 10009, 100009, 1000009, 10000009, 100000009, 1000000009, 10000000009, 100000000009, 1000000000009, 10000000000009, 100000000000009, 1000000000000009, 10000000000000009, 100000000000000009, 1000000000000000009, 10000000000000000009, 100000000000000000009
Offset: 0

Views

Author

Vincenzo Librandi, Dec 30 2014

Keywords

Crossrefs

Cf. similar sequences listed in A253208.
Cf. A170955.

Programs

  • Magma
    [10^n+9: n in [0..30]];
  • Mathematica
    Table[10^n + 9, {n, 0, 40}]
    LinearRecurrence[{11,-10},{10,19},40] (* Harvey P. Dale, Jun 29 2018 *)

Formula

a(n) = 11*a(n-1) - 10*a(n-2) for n > 1.
G.f.: (10 - 91*x)/((1 - x)*(1 - 10*x)).
E.g.f.: exp(x)*(exp(9*x) + 9). - Elmo R. Oliveira, Sep 15 2024

Extensions

a(20) from Elmo R. Oliveira, Sep 15 2024
a(20) corrected by Sean A. Irvine, Sep 22 2024

A253209 a(n) = 6^n + 5.

Original entry on oeis.org

6, 11, 41, 221, 1301, 7781, 46661, 279941, 1679621, 10077701, 60466181, 362797061, 2176782341, 13060694021, 78364164101, 470184984581, 2821109907461, 16926659444741, 101559956668421, 609359740010501, 3656158440062981, 21936950640377861, 131621703842267141
Offset: 0

Views

Author

Vincenzo Librandi, Dec 29 2014

Keywords

Comments

Subsequence of A226814.

Crossrefs

Cf. similar sequences listed in A253208.

Programs

  • Magma
    [6^n+5: n in [0..30]];
  • Mathematica
    Table[6^n + 5, {n, 0, 30}]

Formula

G.f.: (6 - 31*x) / ((1 - x)*(1 - 6*x)).
a(n) = 7*a(n-1) - 6*a(n-2) for n>1.

A253210 a(n) = 7^n + 6.

Original entry on oeis.org

7, 13, 55, 349, 2407, 16813, 117655, 823549, 5764807, 40353613, 282475255, 1977326749, 13841287207, 96889010413, 678223072855, 4747561509949, 33232930569607, 232630513987213, 1628413597910455, 11398895185373149, 79792266297612007, 558545864083284013
Offset: 0

Views

Author

Vincenzo Librandi, Dec 29 2014

Keywords

Comments

Subsequence of A226819.

Crossrefs

Cf. similar sequences listed in A253208.

Programs

  • Magma
    [7^n+6: n in [0..30]];
  • Mathematica
    Table[7^n + 6, {n, 0, 30}]

Formula

G.f.: (7 - 43*x) / ((1 - x)*(1 - 7*x)).
a(n) = 8*a(n-1) - 7*a(n-2) for n>1.

A253212 a(n) = 9^n + 8.

Original entry on oeis.org

9, 17, 89, 737, 6569, 59057, 531449, 4782977, 43046729, 387420497, 3486784409, 31381059617, 282429536489, 2541865828337, 22876792454969, 205891132094657, 1853020188851849, 16677181699666577, 150094635296999129, 1350851717672992097, 12157665459056928809
Offset: 0

Views

Author

Vincenzo Librandi, Dec 30 2014

Keywords

Comments

Subsequence of A226832.

Crossrefs

Cf. similar sequences listed in A253208.

Programs

  • Magma
    [9^n+8: n in [0..30]];
  • Mathematica
    Table[9^n + 8, {n, 0, 40}]
    LinearRecurrence[{10,-9},{9,17},30] (* Harvey P. Dale, Jul 02 2021 *)

Formula

G.f.: (9 - 73*x)/((1 - x)*(1 - 9*x)).
a(n) = 10*a(n-1) - 9*a(n-2) for n>1.
Showing 1-8 of 8 results.