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 1-5 of 5 results.

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

A341413 a(n) = (Sum_{k=1..7} k^n) mod n.

Original entry on oeis.org

0, 0, 1, 0, 3, 2, 0, 4, 1, 0, 6, 8, 2, 0, 4, 4, 11, 14, 9, 16, 7, 8, 5, 20, 8, 10, 1, 0, 28, 20, 28, 4, 25, 4, 14, 32, 28, 26, 4, 36, 28, 20, 28, 12, 28, 2, 28, 20, 0, 0, 19, 48, 28, 32, 34, 28, 43, 24, 28, 56, 28, 16, 28, 4, 18, 20, 28, 52, 25, 0, 28, 68, 28, 66, 19, 40
Offset: 1

Views

Author

Seiichi Manyama, Feb 11 2021

Keywords

Crossrefs

(Sum_{k=1..m} k^n) mod n: A096196 (m=2), A341409 (m=3), A341410 (m=4), A341411 (m=5), A341412 (m=6), this sequence (m=7).

Programs

  • Maple
    a:= n-> add(i&^n, i=1..7) mod n:
    seq(a(n), n=1..100);  # Alois P. Heinz, Feb 11 2021
  • Mathematica
    a[n_] := Mod[Sum[k^n, {k, 1, 7}], n]; Array[a, 100] (* Amiram Eldar, Feb 11 2021 *)
  • PARI
    a(n) = sum(k=1, 7, k^n)%n;

Formula

a(n) = A001554(n) mod n.
a(A056750(n)) = 0.
From Robert Israel, Feb 09 2023: (Start)
Given positive integer k, let m = A001554(k).
If p is a prime > m/k and A001554(p*k) == m (mod k), then a(p*k) = m.
This is true for all primes p > m/k for k = 1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 14, ...
For k = 5 or 15 it is true for primes p > m/k with p == 1 (mod 4).
For k = 11 it is true for primes p > m/k with p == 1 or 7 (mod 10).
For k = 13 it is true for primes p > m/k with p == 1 (mod 12).
(End)

A001555 a(n) = 1^n + 2^n + ... + 8^n.

Original entry on oeis.org

8, 36, 204, 1296, 8772, 61776, 446964, 3297456, 24684612, 186884496, 1427557524, 10983260016, 84998999652, 660994932816, 5161010498484, 40433724284976, 317685943157892, 2502137235710736, 19748255868485844, 156142792528260336, 1236466399775623332
Offset: 0

Views

Author

Keywords

Comments

Conjectures for o.g.f.s for this type of sequence appear in the PhD thesis by Simon Plouffe. See A001552 for the reference. These conjectures are proved in a link given in A196837. [Wolfdieter Lang, Oct 15 2011]

References

  • M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 813.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column 8 of array A103438.

Programs

  • Maple
    seq(add(j^n,j=1..8), n=0..20); # Robert Israel, Aug 23 2015
  • Mathematica
    Table[Total[Range[8]^n], {n, 0, 20}] (* T. D. Noe, Aug 09 2012 *)
  • PARI
    first(m)=vector(m,n,n--;sum(i=1,8,i^n)) \\ Anders Hellström, Aug 23 2015

Formula

From Wolfdieter Lang, Oct 15 2011 (Start)
E.g.f.: (1-exp(8*x))/(exp(-x)-1) = Sum_{j=1..8} exp(j*x) (trivial).
O.g.f.: 4*(2-9*x)*(1-27*x+288*x^2-1539*x^3+4299*x^4-5886*x^5+3044*x^6) / Product_{j=1..8} (1-j*x). From the e.g.f. via Laplace transformation. See the proof in a link under A196837. (End)
a(n) = A001554(n) + A001018(n). - Michel Marcus, Jul 26 2013

Extensions

More terms from Jon E. Schoenfield, Mar 24 2010

A366302 Expansion of e.g.f. 1 / (-6 + Sum_{k=1..7} exp(-k*x)).

Original entry on oeis.org

1, 28, 1428, 108976, 11088924, 1410452848, 215282610348, 38335940184976, 7801807561068444, 1786227911508713008, 454397569178386774668, 127153351764004535348176, 38815768300684586111354364, 12836619471891836987050169968, 4571701128215207034965181098988, 1744488930796462320024115801858576
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 06 2023

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 15; CoefficientList[Series[1/(-6 + Sum[Exp[-k x], {k, 1, 7}]), {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[(-1)^(k + 1) Binomial[n, k] (1 + 2^k + 3^k + 4^k + 5^k + 6^k + 7^k) a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 15}]

Formula

a(0) = 1; a(n) = Sum_{k=1..n} (-1)^(k+1) * binomial(n,k) * (1 + 2^k + ... + 7^k) * a(n-k).

A056750 Numbers n such that n | 7^n + 6^n + 5^n + 4^n + 3^n + 2^n + 1^n.

Original entry on oeis.org

1, 2, 4, 7, 10, 14, 28, 49, 50, 70, 98, 196, 209, 250, 343, 350, 490, 539, 668, 686, 1250, 1309, 1372, 1519, 1750, 1919, 2401, 2450, 2690, 2849, 3430, 4450, 4802, 6250, 8750, 9212, 9590, 9604, 9982, 10717, 12250, 15698, 16807, 17150, 18790, 24010, 31250
Offset: 1

Views

Author

Robert G. Wilson v, Aug 25 2000

Keywords

Crossrefs

Cf. A001554.

Programs

  • Mathematica
    Do[ If[ Mod[ PowerMod[ 7, n, n ] + PowerMod[ 6, n, n ] + PowerMod[ 5, n, n ] + PowerMod[ 4, n, n ] + PowerMod[ 3, n, n ] + PowerMod[ 2, n, n ] + 1, n ] == 0, Print[ n ] ], {n, 1, 10^6} ]
    Select[Range[31500],Divisible[Plus@@(Range[7]^#),#]&] (* or *) Select[ Range[ 31500],Mod[Total[PowerMod[Range[7],#,#]],#]==0&] (* The second program is much faster than the first, and the second program is only a rewrite of the first program above *) (* Harvey P. Dale, Mar 12 2018 *)
Showing 1-5 of 5 results.