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 1-10 of 100 results. Next

A001576 a(n) = 1^n + 2^n + 4^n.

Original entry on oeis.org

3, 7, 21, 73, 273, 1057, 4161, 16513, 65793, 262657, 1049601, 4196353, 16781313, 67117057, 268451841, 1073774593, 4295032833, 17180000257, 68719738881, 274878431233, 1099512676353, 4398048608257, 17592190238721, 70368752566273, 281474993487873, 1125899940397057
Offset: 0

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Author

Keywords

Comments

Equals A135576, except for the first term. - Omar E. Pol, Nov 18 2008
Conjecture: For n > 1, if a(n) = 1^n + 2^n + 4^n is a prime number then n is of the form 3^h. For example, for h=1, n=3, a(n) = 1^3 + 2^3 + 4^3 = 73 (prime); for h=2, n=9, a(n) = 1^9 + 2^9 + 4^9 = 262657 (prime); for h=3, n=27, a(n) is not prime. - Vincenzo Librandi, Aug 03 2010
The previous conjecture was proved by Golomb in 1978. See A051154. - T. D. Noe, Aug 15 2010
Another more elementary proof can be found in Liu link. - Bernard Schott, Mar 08 2019
Fills in one quarter section of the figurate form of the Sierpinski square curve. See illustration in links and A141725. - John Elias, Mar 29 2023

Crossrefs

Subsequence of A002061.
See also comments in A051154.

Programs

Formula

a(n) = 6*a(n-1) - 8*a(n-2) + 3.
O.g.f.: -1/(-1+x) - 1/(-1+2*x) - 1/(-1+4*x) = ( -3+14*x-14*x^2 ) / ( (x-1)*(2*x-1)*(4*x-1) ). - R. J. Mathar, Feb 29 2008
E.g.f.: e^x + e^(2*x) + e^(4*x). - Mohammad K. Azarian, Dec 26 2008
a(n) = A024088(n)/A000225(n). - Reinhard Zumkeller, Feb 15 2009
Exp( Sum_{n >= 1} a(n)*x^n/n ) = 1 + 7*x + 35*x^2 + 155*x^3 + ... is the o.g.f. for the 2nd subdiagonal of triangle A022166, essentially A006095. - Peter Bala, Apr 07 2015

A074501 a(n) = 1^n + 2^n + 5^n.

Original entry on oeis.org

3, 8, 30, 134, 642, 3158, 15690, 78254, 390882, 1953638, 9766650, 48830174, 244144722, 1220711318, 6103532010, 30517610894, 152587956162, 762939584198, 3814697527770, 19073486852414, 95367432689202, 476837160300278
Offset: 0

Views

Author

Robert G. Wilson v, Aug 23 2002

Keywords

Crossrefs

Programs

Formula

From Mohammad K. Azarian, Dec 26 2008: (Start)
G.f.: 1/(1-x) + 1/(1-2*x) + 1/(1-5*x).
E.g.f.: e^x + e^(2*x) + e^(5*x). (End)
a(n) = 7*a(n-1) - 10*a(n-2) + 4 with a(0)=3, a(1)=8. - Vincenzo Librandi, Jul 21 2010

A007689 a(n) = 2^n + 3^n.

Original entry on oeis.org

2, 5, 13, 35, 97, 275, 793, 2315, 6817, 20195, 60073, 179195, 535537, 1602515, 4799353, 14381675, 43112257, 129271235, 387682633, 1162785755, 3487832977, 10462450355, 31385253913, 94151567435, 282446313697, 847322163875
Offset: 0

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Author

Keywords

References

  • L. B. W. Jolley, Summation of Series, Dover Publications, 1961, p. 14.
  • D. E. Knuth, The Art of Computer Programming. Addison-Wesley, Reading, MA, Vol. 1, p. 92.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

For odd-indexed members divided by 5 see A096951.
Binomial transform of A000051.
Cf. A074600 - A074624, A082101 (primes).

Programs

Formula

E.g.f.: exp(2*x)*(1+exp(x)).
G.f.: (2-5*x)/((1-2*x)*(1-3*x)).
a(n) = 5*a(n-1) - 6*a(n-2).
Sum_{j=0..n-1} a(j) = (1/2)*(3^n - 1) + (2^n - 1). [Jolley] - Gary W. Adamson, Dec 20 2006
Equals double binomial transform of [2, 1, 1, 1, ...]. - Gary W. Adamson, Apr 23 2008
If p[i] = Fibonacci(2i-5) and if A is the Hessenberg matrix of order n defined by: A[i,j]=p[j-i+1], (i<=j), A[i,j]=-1, (i=j+1), and A[i,j]=0 otherwise. Then, for n>=1, a(n-1)= det A. - Milan Janjic, May 08 2010
a(n) = 2*a(n-1) + 3^(n-1), with a(0)=2. - Vincenzo Librandi, Nov 18 2010
a(n) = A001550(n) - 1 = A000079(n) + A000244(n). - Reinhard Zumkeller, Mar 01 2012

Extensions

Additional comments from Michael Somos, Jun 10 2000

A034513 a(n) = 1^n + 3^n + 9^n.

Original entry on oeis.org

3, 13, 91, 757, 6643, 59293, 532171, 4785157, 43053283, 387440173, 3486843451, 31381236757, 282430067923, 2541867422653, 22876797237931, 205891146443557, 1853020231898563, 16677181828806733, 150094635684419611
Offset: 0

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Author

Keywords

Comments

Also the sum of n-th powers of the divisors of 9.

Crossrefs

Programs

Formula

G.f.: 1/(1-x)+1/(1-3*x)+1/(1-9*x). E.g.f.: e^x+e^(3*x)+e^(9*x). - Mohammad K. Azarian, Dec 26 2008
a(n) = 13*a(n-1) - 39*a(n-2) + 27*a(n-3), a(0)=3, a(1)=13, a(2)=91. - Harvey P. Dale, Apr 13 2012

A074580 a(n) = 7^n + 8^n + 9^n.

Original entry on oeis.org

3, 24, 194, 1584, 13058, 108624, 911234, 7703664, 65588738, 561991824, 4843001474, 41948320944, 364990300418, 3188510652624, 27953062038914, 245823065693424, 2167728096132098, 19161612027339024, 169737447404391554
Offset: 0

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Author

Robert G. Wilson v, Aug 23 2002

Keywords

Crossrefs

Programs

Formula

From Mohammad K. Azarian, Dec 26 2008: (Start)
G.f.: 1/(1-7*x) + 1/(1-8*x) + 1/(1-9*x).
E.g.f.: e^(7*x) + e^(8*x) + e^(9*x). (End)

A001579 a(n) = 3^n + 5^n + 6^n.

Original entry on oeis.org

3, 14, 70, 368, 2002, 11144, 63010, 360248, 2076802, 12050504, 70290850, 411802328, 2421454402, 14282991464, 84472462690, 500716911608, 2973740844802, 17689728038024, 105375041354530, 628434388600088
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Magma
    [3^n + 5^n + 6^n: n in [0..20]]; // Vincenzo Librandi, May 20 2011
    
  • Mathematica
    Table[3^n + 5^n + 6^n, {n, 0, 20}]
    LinearRecurrence[{14,-63,90},{3,14,70},20] (* Harvey P. Dale, Jun 17 2021 *)
  • PARI
    a(n)=3^n+5^n+6^n \\ Charles R Greathouse IV, Jun 10 2011
    
  • Python
    def a(n): return 3**n + 5**n + 6**n
    print([a(n) for n in range(20)]) # Michael S. Branicky, Mar 14 2021

Formula

From Mohammad K. Azarian, Dec 26 2008: (Start)
G.f.: 1/(1-3*x) + 1/(1-5*x) + 1/(1-6*x).
E.g.f.: e^(3*x) + e^(5*x) + e^(6*x). (End)

A103438 Square array T(m,n) read by antidiagonals: Sum_{k=1..n} k^m.

Original entry on oeis.org

0, 0, 1, 0, 1, 2, 0, 1, 3, 3, 0, 1, 5, 6, 4, 0, 1, 9, 14, 10, 5, 0, 1, 17, 36, 30, 15, 6, 0, 1, 33, 98, 100, 55, 21, 7, 0, 1, 65, 276, 354, 225, 91, 28, 8, 0, 1, 129, 794, 1300, 979, 441, 140, 36, 9, 0, 1, 257, 2316, 4890, 4425, 2275, 784, 204, 45, 10
Offset: 0

Views

Author

Ralf Stephan, Feb 11 2005

Keywords

Comments

For the o.g.f.s of the column sequences for this array, see A196837 and the link given there. - Wolfdieter Lang, Oct 15 2011
T(m,n)/n is the m-th moment of the discrete uniform distribution on {1,2,...,n}. - Geoffrey Critzer, Dec 31 2018
T(1,n) divides T(m,n) for odd m. - Franz Vrabec, Dec 23 2020

Examples

			Square array begins:
  0, 1,  2,   3,    4,     5,     6,      7,      8,      9, ... A001477;
  0, 1,  3,   6,   10,    15,    21,     28,     36,     45, ... A000217;
  0, 1,  5,  14,   30,    55,    91,    140,    204,    285, ... A000330;
  0, 1,  9,  36,  100,   225,   441,    784,   1296,   2025, ... A000537;
  0, 1, 17,  98,  354,   979,  2275,   4676,   8772,  15333, ... A000538;
  0, 1, 33, 276, 1300,  4425, 12201,  29008,  61776, 120825, ... A000539;
  0, 1, 65, 794, 4890, 20515, 67171, 184820, 446964, 978405, ... A000540;
Antidiagonal triangle begins as:
  0;
  0, 1;
  0, 1,  2;
  0, 1,  3,  3;
  0, 1,  5,  6,  4;
  0, 1,  9, 14, 10,  5;
  0, 1, 17, 36, 30, 15, 6;
		

References

  • J. Faulhaber, Academia Algebrae, Darinnen die miraculosische inventiones zu den höchsten Cossen weiters continuirt und profitirt werden, Augspurg, bey Johann Ulrich Schönigs, 1631.

Crossrefs

Diagonals include A076015 and A031971.
Antidiagonal sums are in A103439.
Antidiagonals are the rows of triangle A192001.

Programs

  • Magma
    T:= func< n,k | n eq 0 select k else (&+[j^n: j in [0..k]]) >;
    [T(n-k,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Dec 22 2021
    
  • Maple
    seq(print(seq(Zeta(0,-k,1)-Zeta(0,-k,n+1),n=0..9)),k=0..6);
    # (Produces the square array from the example.) Peter Luschny, Nov 16 2008
    # alternative
    A103438 := proc(m,n)
        (bernoulli(m+1,n+1)-bernoulli(m+1))/(m+1) ;
        if m = 0 then
            %-1 ;
        else
            % ;
        end if;
    end proc: # R. J. Mathar, May 10 2013
    # simpler:
    A103438 := proc(m,n)
        (bernoulli(m+1,n+1)-bernoulli(m+1,1))/(m+1) ;
    end proc: # Peter Luschny, Mar 20 2024
  • Mathematica
    T[m_, n_]:= HarmonicNumber[m, -n]; Flatten[Table[T[m-n, n], {m, 0, 11}, {n, m, 0, -1}]] (* Jean-François Alcover, May 11 2012 *)
  • PARI
    T(m,n)=sum(k=0,n,k^m)
    
  • Python
    from itertools import count, islice
    from math import comb
    from fractions import Fraction
    from sympy import bernoulli
    def A103438_T(m,n): return sum(k**m for k in range(1,n+1)) if n<=m else int(sum(comb(m+1,i)*(bernoulli(i) if i!=1 else Fraction(1,2))*n**(m-i+1) for i in range(m+1))/(m+1))
    def A103438_gen(): # generator of terms
        for m in count(0):
            for n in range(m+1):
                yield A103438_T(m-n,n)
    A103438_list = list(islice(A103438_gen(),100)) # Chai Wah Wu, Oct 23 2024
  • SageMath
    def T(n,k): return (bernoulli_polynomial(k+1, n+1) - bernoulli_polynomial(1, n+1)) /(n+1)
    flatten([[T(n-k,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Dec 22 2021
    

Formula

E.g.f.: e^x*(e^(x*y)-1)/(e^x-1).
T(m, n) = Zeta(-n, 1) - Zeta(-n, m + 1), for m >= 0 and n >= 0, where Zeta(z, v) is the Hurwitz zeta function. - Peter Luschny, Nov 16 2008
T(m, n) = HarmonicNumber(m, -n). - Jean-François Alcover, May 11 2012
T(m, n) = (Bernoulli(m + 1, n + 1) - Bernoulli(m + 1, 1)) / (m + 1). - Peter Luschny, Mar 20 2024
T(m, n) = Sum_{k=0...m-n} B(k)*(-1)^k*binomial(m-n,k)*n^(m-n-k+1)/(m-n-k+1), where B(k) = Bernoulli number A027641(k) / A027642(k). - Robert B Fowler, Aug 20 2024
T(m, n) = Sum_{i=1..n} J_m(i)*floor(n/i), where J_m is the m-th Jordan totient function. - Ridouane Oudra, Jul 19 2025

A144048 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is Euler transform of (j->j^k).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 5, 6, 5, 1, 1, 9, 14, 13, 7, 1, 1, 17, 36, 40, 24, 11, 1, 1, 33, 98, 136, 101, 48, 15, 1, 1, 65, 276, 490, 477, 266, 86, 22, 1, 1, 129, 794, 1828, 2411, 1703, 649, 160, 30, 1, 1, 257, 2316, 6970, 12729, 11940, 5746, 1593, 282, 42, 1, 1, 513
Offset: 0

Views

Author

Alois P. Heinz, Sep 08 2008

Keywords

Comments

In general, column k > 0 is asymptotic to (Gamma(k+2)*Zeta(k+2))^((1-2*Zeta(-k)) /(2*k+4)) * exp((k+2)/(k+1) * (Gamma(k+2)*Zeta(k+2))^(1/(k+2)) * n^((k+1)/(k+2)) + Zeta'(-k)) / (sqrt(2*Pi*(k+2)) * n^((k+3-2*Zeta(-k))/(2*k+4))). - Vaclav Kotesovec, Mar 01 2015

Examples

			Square array begins:
  1,  1,   1,   1,    1,     1, ...
  1,  1,   1,   1,    1,     1, ...
  2,  3,   5,   9,   17,    33, ...
  3,  6,  14,  36,   98,   276, ...
  5, 13,  40, 136,  490,  1828, ...
  7, 24, 101, 477, 2411, 12729, ...
		

Crossrefs

Rows give: 0-1: A000012, 2: A000051, A094373, 3: A001550, 4: A283456, 5: A283457.
Main diagonal gives A252782.
Cf. A283272.

Programs

  • Maple
    with(numtheory): etr:= proc(p) local b; b:= proc(n) option remember; `if`(n=0,1, add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n) end end: A:= (n,k)-> etr(j->j^k)(n); seq(seq(A(n,d-n), n=0..d), d=0..13);
  • Mathematica
    etr[p_] := Module[{ b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[j]}]*b[n - j], {j, 1, n}]/n]; b]; A[n_, k_] := etr[Function[j, j^k]][n]; Table[Table[A[n, d - n], {n, 0, d}], {d, 0, 13}] // Flatten (* Jean-François Alcover, Dec 27 2013, translated from Maple *)

Formula

G.f. of column k: Product_{j>=1} 1/(1-x^j)^(j^k).

A074527 a(n) = 2^n + 3^n + 5^n.

Original entry on oeis.org

3, 10, 38, 160, 722, 3400, 16418, 80440, 397442, 1973320, 9825698, 49007320, 244676162, 1222305640, 6108314978, 30531959800, 152631002882, 763068724360, 3815084948258, 19074649113880, 95370919473602, 476847620653480
Offset: 0

Views

Author

Robert G. Wilson v, Aug 23 2002

Keywords

Crossrefs

Programs

Formula

From Mohammad K. Azarian, Dec 26 2008: (Start)
G.f.: 1/(1-2*x) + 1/(1-3*x) + 1/(1-5*x).
E.g.f.: exp(2*x) + exp(3*x) + exp(5*x). (End)
a(n) = 10*a(n-1) - 31*a(n-2) + 30*a(n-3). - Wesley Ivan Hurt, May 26 2024

A083321 a(n) = (-1)^n + (-2)^n - (-3)^n.

Original entry on oeis.org

1, 0, -4, 18, -64, 210, -664, 2058, -6304, 19170, -58024, 175098, -527344, 1586130, -4766584, 14316138, -42981184, 129009090, -387158344, 1161737178, -3485735824, 10458256050, -31376865304, 94134790218, -282412759264, 847255055010, -2541798719464, 7625463267258
Offset: 0

Views

Author

Paul Barry, Apr 25 2003

Keywords

Crossrefs

Cf. A001550 (1^n + 2^n + 3^n).

Programs

Formula

G.f.: (1+6*x+7*x^2)/((1+x)*(1+2*x)*(1+3*x)).
E.g.f.: exp(-x)+exp(-2*x)-exp(-3*x).
a(n) = (-1)^(n-1)*(3^n - 2^n - 1) for n >= 0. - M. F. Hasler, Apr 19 2020
Showing 1-10 of 100 results. Next