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 10 results.

A000584 Fifth powers: a(n) = n^5.

Original entry on oeis.org

0, 1, 32, 243, 1024, 3125, 7776, 16807, 32768, 59049, 100000, 161051, 248832, 371293, 537824, 759375, 1048576, 1419857, 1889568, 2476099, 3200000, 4084101, 5153632, 6436343, 7962624, 9765625, 11881376, 14348907, 17210368, 20511149
Offset: 0

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Author

Keywords

Comments

Totally multiplicative sequence with a(p) = p^5 for prime p. - Jaroslav Krizek, Nov 01 2009
The binomial transform yields A059338. The inverse binomial transform yields the (finite) 0, 1, 30, 150, 240, 120, the 5th row in A019538 and A131689. - R. J. Mathar, Jan 16 2013
Equals sum of odd numbers from n^2*(n-1)+1 (A100104) to n^2*(n+1)-1 (A003777). - Bruno Berselli, Mar 14 2014
a(n) mod 10 = n mod 10. - Reinhard Zumkeller, May 10 2014
Numbers of the form a(n) + a(n+1) + ... + a(n+k) are nonprime for all n, k>=0; this can be proved by the method indicated in the comment in A256581. - Vladimir Shevelev and Peter J. C. Moses, Apr 04 2015

References

  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. Addison-Wesley, Reading, MA, 1990, p. 255; 2nd. ed., p. 269. Worpitzky's identity (6.37).
  • 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

Partial sums give A000539.

Programs

Formula

G.f.: x*(1+26*x+66*x^2+26*x^3+x^4) / (x-1)^6. [Simon Plouffe in his 1992 dissertation]
Multiplicative with a(p^e) = p^(5e). - David W. Wilson, Aug 01 2001
E.g.f.: exp(x)*(x+15*x^2+25*x^3+10*x^4+x^5). - Geoffrey Critzer, Jun 12 2013
a(n) = 5*a(n-1) - 10* a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) + 120. - Ant King, Sep 23 2013
a(n) = n + Sum_{j=0..n-1}{k=1..4}binomial(5,k)*j^(5-k). - Patrick J. McNab, Mar 28 2016
From Kolosov Petro, Oct 22 2018: (Start)
a(n) = Sum_{k=1..n} A300656(n,k).
a(n) = Sum_{k=0..n-1} A300656(n,k). (End)
a(n) = Sum_{k=1..5} Eulerian(5, k)*binomial(n+5-k, 5), with Eulerian(5, k) = A008292(5, k), the numbers 1, 26, 66, 26, 1, for n >= 0. Worpitzki's identity for powers of 5. See. e.g., Graham et al., eq. (6, 37) (using A173018, the row reversed version of A123125). - Wolfdieter Lang, Jul 17 2019
From Amiram Eldar, Oct 08 2020: (Start)
Sum_{n>=1} 1/a(n) = zeta(5) (A013663).
Sum_{n>=1} (-1)^(n+1)/a(n) = 15*zeta(5)/16 (A267316). (End)

Extensions

More terms from Henry Bottomley, Jun 21 2001

A136676 Numerator of Sum_{k=1..n} (-1)^(k+1)/k^5.

Original entry on oeis.org

1, 31, 7565, 241837, 755989457, 755889457, 12705011703799, 406547611705943, 98792790681344149, 98791774426324117, 15910615688635928566967, 15910549913780913466967, 5907492176026179821253778331
Offset: 1

Views

Author

Alexander Adamchuk, Jan 16 2008

Keywords

Comments

a(n) is prime for n in A136685.
Lim_{n -> infinity} a(n)/A334604(n) = A267316 = (15/16)*A013663. - Petros Hadjicostas, May 07 2020

Examples

			The first few fractions are 1, 31/32, 7565/7776, 241837/248832, 755989457/777600000, 755889457/777600000, ... = a(n)/A334604(n). - _Petros Hadjicostas_, May 07 2020
		

Crossrefs

Programs

  • Mathematica
    Table[ Numerator[ Sum[ (-1)^(k+1)/k^5, {k,1,n} ] ], {n,1,30} ]
  • PARI
    a(n) = numerator(sum(k=1, n, (-1)^(k+1)/k^5)); \\ Michel Marcus, May 07 2020

A275703 Decimal expansion of the Dirichlet eta function at 6.

Original entry on oeis.org

9, 8, 5, 5, 5, 1, 0, 9, 1, 2, 9, 7, 4, 3, 5, 1, 0, 4, 0, 9, 8, 4, 3, 9, 2, 4, 4, 4, 8, 4, 9, 5, 4, 2, 6, 1, 4, 0, 4, 8, 8, 5, 6, 9, 3, 4, 6, 9, 3, 2, 6, 8, 8, 8, 0, 3, 4, 8, 3, 3, 3, 9, 3, 2, 5, 4, 1, 9, 6, 8, 0, 2, 1, 8, 6, 2, 7, 1, 7, 1, 3, 5, 7, 3, 9, 3, 7, 2, 9, 1, 1, 2, 7, 9, 5, 5, 9, 4, 6, 4
Offset: 0

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Author

Terry D. Grant, Aug 05 2016

Keywords

Comments

It appears that each sum of a Dirichlet eta function is 1/2^(x-1) less than the zeta(x), where x is a positive integer > 1. In this case, eta(x) = eta(6) = (31/32)*zeta(6) = 31*(Pi^6)/30240. Therefore eta(6) = 1/2^(6-1) or 1/32nd less than zeta(6) (see A013664). [Edited by Petros Hadjicostas, May 07 2020]

Examples

			31*(Pi^6)/30240 = 0.9855510912974...
		

Crossrefs

Cf. A002162 (decimal expansion of value at 1), A072691 (value at 2), A197070 (value at 3), A267315 (value at 4), A267316 (value at 5), A275710 (value at 7).

Programs

  • Mathematica
    RealDigits[31*(Pi^6)/30240,10,100]
  • Sage
    s = RLF(0); s
    RealField(110)(s)
    for i in range(1, 10000): s -= (-1)^i / i^6
    print(s) # Terry D. Grant, Aug 05 2016

Formula

eta(6) = 31*(Pi^6)/30240 = 31*A092732/30240 = Sum_{n>=1} (-1)^(n+1)/n^6.
eta(6) = lim_{n -> infinity} A136677(n)/A334605(n). - Petros Hadjicostas, May 07 2020

A275710 Decimal expansion of the Dirichlet eta function at 7.

Original entry on oeis.org

9, 9, 2, 5, 9, 3, 8, 1, 9, 9, 2, 2, 8, 3, 0, 2, 8, 2, 6, 7, 0, 4, 2, 5, 7, 1, 3, 1, 3, 3, 3, 9, 3, 6, 8, 5, 2, 3, 1, 1, 1, 5, 6, 9, 2, 4, 3, 1, 4, 0, 6, 8, 5, 1, 6, 2, 9, 5, 1, 3, 0, 8, 7, 5, 6, 2, 6, 7, 0, 2, 0, 5, 2, 1, 8, 6, 4, 7, 0, 5, 1, 9, 8, 1, 3, 1, 4, 2, 0, 3, 7, 7, 4, 5, 7, 2, 3, 9, 7, 0
Offset: 0

Views

Author

Terry D. Grant, Aug 06 2016

Keywords

Examples

			0.99259381992283028267...
		

Crossrefs

Cf. A002162 (value at 1), A013665, A072691 (value at 2), A197070 (value at 3), A267315 (value at 4), A267316 (value at 5), A275703 (value at 6), A334668, A334669, A347150, A347059.

Programs

  • Mathematica
    RealDigits[63 Zeta[7]/64, 10, 100] [[1]]
  • PARI
    -polylog(7, -1) \\ Michel Marcus, Aug 20 2021
  • Sage
    s = RLF(0); s
    RealField(110)(s)
    for i in range(1, 10000): s -= (-1)^i / i^7
    print(s) # Terry D. Grant, Aug 06 2016
    

Formula

eta(7) = 63*zeta(7)/64 = (63*A013665)/64.
eta(7) = Lim_{n -> infinity} A334668(n)/A334669(n). - Petros Hadjicostas, May 07 2020
Equals Sum_{k>=1} (-1)^(k+1) / k^7. - Sean A. Irvine, Aug 19 2021

A334604 Denominator of Sum_{k=1..n} (-1)^(k+1)/k^5.

Original entry on oeis.org

1, 32, 7776, 248832, 777600000, 777600000, 13069123200000, 418211942400000, 101625502003200000, 101625502003200000, 16366888723117363200000, 16366888723117363200000, 6076911214672415134617600000
Offset: 1

Views

Author

Petros Hadjicostas, May 07 2020

Keywords

Comments

Lim_{n -> infinity} A136676(n)/a(n) = A267316 = (15/16)*A013663.

Examples

			The first few fractions are 1, 31/32, 7565/7776, 241837/248832, 755989457/777600000, 755889457/777600000, ... = A136676/A334604.
		

Crossrefs

Cf. A013663, A136676 (numerators), A267316.

Programs

  • Mathematica
    Denominator @ Accumulate[Table[(-1)^(k + 1)/k^5, {k, 1, 13}]] (* Amiram Eldar, May 08 2020 *)
  • PARI
    a(n) = denominator(sum(k=1, n, (-1)^(k+1)/k^5)); \\ Michel Marcus, May 07 2020

A347059 Decimal expansion of the Dirichlet eta function at 9.

Original entry on oeis.org

9, 9, 8, 0, 9, 4, 2, 9, 7, 5, 4, 1, 6, 0, 5, 3, 3, 0, 7, 6, 7, 7, 8, 3, 0, 3, 1, 8, 5, 2, 5, 9, 7, 9, 5, 0, 8, 7, 4, 3, 3, 3, 9, 5, 3, 5, 3, 7, 8, 7, 7, 4, 7, 2, 3, 4, 3, 3, 2, 8, 6, 6, 0, 3, 7, 8, 8, 8, 7, 4, 5, 5, 5, 2, 5, 4, 5, 2, 7, 0, 2, 0, 7, 9, 4, 9, 3
Offset: 0

Views

Author

Sean A. Irvine, Aug 14 2021

Keywords

Examples

			0.998094297541605330767783031852597950...
		

References

  • L. B. W. Jolley, Summation of Series, Dover, 1961, Eq. (306).

Crossrefs

Programs

  • Mathematica
    First[RealDigits[N[DirichletEta[9],87]]] (* Stefano Spezia, Aug 15 2021 *)
  • PARI
    -polylog(9, -1) \\ Michel Marcus, Aug 15 2021

Formula

Equals (255/256) * zeta(9).
Equals Sum_{k>=1} (-1)^(k+1) / k^9.
Equals eta(9).

A347150 Decimal expansion of the Dirichlet eta function at 8.

Original entry on oeis.org

9, 9, 6, 2, 3, 3, 0, 0, 1, 8, 5, 2, 6, 4, 7, 8, 9, 9, 2, 2, 7, 2, 8, 9, 2, 6, 0, 0, 8, 2, 8, 0, 3, 6, 1, 7, 8, 7, 4, 1, 2, 5, 1, 5, 9, 4, 7, 2, 8, 9, 8, 0, 6, 7, 0, 4, 5, 2, 8, 9, 0, 2, 9, 1, 9, 4, 3, 5, 9, 6, 4, 8, 2, 5, 7, 7, 5, 8, 5, 8, 9, 2, 8, 2, 8, 2, 4
Offset: 0

Views

Author

Sean A. Irvine, Aug 19 2021

Keywords

Examples

			0.9962330018526478992272892600828036178741251594728980...
		

References

  • L. B. W. Jolley, Summation of Series, Dover, 1961, Eq. (306).

Crossrefs

Programs

  • Mathematica
    RealDigits[DirichletEta[8], 10, 100][[1]] (* Amiram Eldar, Aug 20 2021 *)
  • PARI
    -polylog(8, -1) \\ Michel Marcus, Aug 20 2021

Formula

Equals (127/128) * zeta(8).
Equals 127 * Pi^8 / 1209600.
Equals Sum_{k>=1} (-1)^(k+1) / k^8.
Equals eta(8).

A346927 Decimal expansion of the Dirichlet eta function at 10.

Original entry on oeis.org

9, 9, 9, 0, 3, 9, 5, 0, 7, 5, 9, 8, 2, 7, 1, 5, 6, 5, 6, 3, 9, 2, 2, 1, 8, 4, 5, 6, 9, 9, 3, 4, 1, 8, 3, 1, 4, 2, 5, 9, 2, 9, 6, 4, 9, 6, 6, 6, 8, 9, 0, 6, 4, 7, 1, 0, 6, 8, 9, 4, 8, 7, 5, 5, 0, 6, 1, 4, 2, 4, 5, 8, 3, 8, 4, 0, 3, 8, 1, 2, 4, 4, 0, 7, 9, 8, 5
Offset: 0

Views

Author

Sean A. Irvine, Aug 07 2021

Keywords

Examples

			0.999039507598271565639221845699341831425929649666890...
		

References

  • L. B. W. Jolley, Summation of Series, Dover, 1961, Eq. (306).

Crossrefs

Programs

  • Mathematica
    RealDigits[DirichletEta[10], 10, 100][[1]] (* Amiram Eldar, Aug 08 2021 *)
  • PARI
    -polylog(10, -1) \\ Michel Marcus, Aug 08 2021

Formula

Equals 73 * Pi^10 / (2^9 * 3^5 * 5 * 11).
Equals (511/512) * zeta(10).
Equals Sum_{k>=1} (-1)^(k+1) / k^10.
Equals eta(10).

A246967 Decimal expansion of the real positive solution to eta(x) = x.

Original entry on oeis.org

6, 2, 9, 3, 3, 4, 0, 9, 4, 0, 0, 9, 3, 7, 2, 7, 6, 7, 5, 5, 6, 4, 8, 0, 5, 0, 2, 5, 8, 9, 3, 2, 6, 1, 3, 7, 6, 4, 7, 2, 0, 7, 6, 4, 6, 8, 6, 6, 1, 8, 5, 3, 5, 5, 0, 6, 8, 8, 5, 8, 0, 2, 3, 1, 9, 7, 2, 6, 9, 2, 8, 5, 2, 9, 1, 5, 5, 7, 4, 6, 2, 1, 1, 0, 4, 2, 0, 0, 7, 9, 7, 5, 5, 6, 1, 9, 4
Offset: 0

Views

Author

Michal Paulovic, Sep 08 2014

Keywords

Comments

Fixed point of Dirichlet eta function.

Examples

			0.6293340940...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[x /. FindRoot[DirichletEta[x] - x, {x, 0}, WorkingPrecision -> 120], 10, 100] [[1]] (* Amiram Eldar, May 24 2021 *)
  • PARI
    solve(n=0,2,(1-2^(1-n))*zeta(n)-n) \\ Edward Jiang, Sep 08 2014

A269482 Continued fraction expansion of the Dirichlet eta function at 5.

Original entry on oeis.org

0, 1, 34, 1, 6, 1, 1, 3, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 2, 2, 2, 35, 3, 1, 5, 4, 1, 2, 2, 1, 4, 1, 1, 1, 2, 10, 2, 1, 6, 9, 23, 1, 5, 1, 1, 1, 1, 1, 2, 1, 3, 4, 1, 2, 1, 1, 2, 2, 1, 1, 5, 4, 7, 1, 1, 1, 1, 2, 2, 1, 4, 1, 1, 2, 8, 3, 2, 1, 3, 1, 5, 356, 2, 57, 6, 1, 6, 1, 1, 31, 1, 5, 1, 1, 477, 1, 9, 7, 3, 4
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 27 2016

Keywords

Comments

Continued fraction of Sum_{k>=1} (-1)^(k - 1)/k^5 = (15*zeta(5))/16 = 0.9721197704469093...

Examples

			1/1^5 - 1/2^5 + 1/3^5 - 1/4^5 + 1/5^5 - 1/6^5 +... = 1/(1 + 1/(34 + 1/(1 + 1/(6 + 1/(1 + 1/(1 + 1/...)))))).
		

Crossrefs

Programs

  • Mathematica
    ContinuedFraction[(15 Zeta[5])/16, 100]
Showing 1-10 of 10 results.