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 29 results. Next

A185673 Least number k having n representations as the sum of the minimal number of biquadrates A002377(k).

Original entry on oeis.org

1, 259, 518, 777, 3402, 3645, 3726, 7045, 7243, 12683, 16441, 13723, 13792, 21631, 20202, 23002, 24135, 27162, 28870, 28215, 33230, 39629, 36510, 41561, 43241, 29563, 47401, 41310, 47150, 47790, 56749, 43962, 48750, 62681, 65069, 50442
Offset: 1

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Author

Martin Renner, Feb 09 2011

Keywords

Comments

This sequence is not monotonically increasing: a(21)=33230 > a(26)=29563.

Examples

			a(1) = 1 since 1 = 1^4 (1 way with minimal representation)
a(2) = 259 since 259 = 1^4 + 1^4 + 1^4 + 4^4 = 2^4 + 3^4 + 3^4 + 3^4 (2 ways with minimal representation)
a(3) = 518 since 518 = 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 1^4 + 4^4 + 4^4 = 1^4 + 1^4 + 1^4 + 2^4 + 3^4 + 3^4 + 3^4 + 4^4 = 2^4 + 2^4 + 3^4 + 3^4 + 3^4 + 3^4 + 3^4 + 3^4 (3 ways with minimal representation)
		

Crossrefs

Cf. A002377.

Programs

  • Mathematica
    t=Table[r=PowersRepresentations[n,19,4]; Sort[Tally[19-Count[#,0]&/@r]][[1,2]], {n,800}]; u=Union[t]; c=Complement[Range[Max[u]],u]; If[c=={}, mx=u[[-1]], mx=c[[1]]-1]; Flatten[Table[Position[t,n,1,1],{n,mx}]]

Extensions

a(10)-a(36) from Alois P. Heinz, Feb 10 2011

A002804 (Presumed) solution to Waring's problem: g(n) = 2^n + floor((3/2)^n) - 2.

Original entry on oeis.org

1, 4, 9, 19, 37, 73, 143, 279, 548, 1079, 2132, 4223, 8384, 16673, 33203, 66190, 132055, 263619, 526502, 1051899, 2102137, 4201783, 8399828, 16794048, 33579681, 67146738, 134274541, 268520676, 536998744, 1073933573, 2147771272, 4295398733, 8590581749
Offset: 1

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Author

Keywords

Comments

g(n) is the smallest number s such that every natural number is the sum of at most s n-th powers of natural numbers.
It is known (Kubina and Wunderlich, 1990) that g(n) = 2^n + floor((3/2)^n) - 2 for all n <= 471600000. This formula is conjectured to be correct for all n (see A174420).
Mahler showed that there are only finitely many n's for which this formula fails. - Tomohiro Yamada, Sep 23 2017
This sequence (which corresponds to Waring's original conjecture) is much easier to compute than A079611, the problem of finding the minimal s = G(n) for almost all (= sufficienly large) integers. See Wikipedia for a one-line proof that this value for g(n), conjectured by J. A. Euler in 1772, is indeed a lower bound; it is known to be tight if 2^n*frac((3/2)^n) + floor((3/2)^n) <= 2^n, and no counterexample to this inequality is known. - M. F. Hasler, Jun 29 2014

References

  • Calvin C. Clawson, Mathematical Mysteries: The Beauty and Magic of Numbers (Basic Books 1996) 252-257.
  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 2.30.1, p. 195.
  • G. H. Hardy, Collected Papers. Vols. 1-, Oxford Univ. Press, 1966-; see vol. 1, p. 668.
  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 337.
  • S. Pillai, On Waring's Problem, Journal of Indian Math. Soc., 2 (1936), 16-44
  • J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 138.
  • P. Ribenboim, The Book of Prime Number Records. Springer-Verlag, NY, 2nd ed., 1989, p. 239.
  • 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).
  • James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, pages 249-250.
  • R. C. Vaughan and T. D. Wooley, Waring's problem: a survey, pp. 285-324 of Surveys in Number Theory (Urbana, May 21, 2000), ed. M. A. Bennett et al., Peters, 2003.
  • Edward Waring, Meditationes algebraicae, Cantabrigiae: typis Academicis excudebat J. Archdeacon, 1770.

Crossrefs

Cf. A002376, A002377, A079611, A174406, A174420, A297446 (for info on Mathematica functions).

Programs

A046042 Number of partitions of n into fourth powers.

Original entry on oeis.org

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

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Keywords

Comments

In general, the number of partitions of n into perfect s-th powers (s>=1) is asymptotic to (2*Pi)^(-(s+1)/2) * sqrt(s/(s+1)) * k * n^(1/(s+1)-3/2) * exp((s+1)*k*n^(1/(s+1))), where k = (Gamma(1 + 1/s) * Zeta(1 + 1/s) / s)^(s/(s+1)) [Hardy & Ramanujan, 1917]. - Vaclav Kotesovec, Dec 29 2016

Examples

			a(33) = 3 because we have [16,16,1], [16,1,1,...,1] (17 1's) and [1,1,...,1] (33 1's).
		

References

  • H. P. Robinson, Letter to N. J. A. Sloane, Jan 04 1974.

Crossrefs

Programs

  • Haskell
    a046042 = p $ tail a000583_list where
       p _          0 = 1
       p ks'@(k:ks) m = if m < k then 0 else p ks' (m - k) + p ks m
    -- Reinhard Zumkeller, May 18 2015   ~
  • Maple
    g:=-1+1/product(1-x^(j^4),j=1..10): gser:=series(g,x=0,105): seq(coeff(gser,x,n),n=1..102); # Emeric Deutsch, Apr 06 2006
  • Mathematica
    g = -1 + 1/Product[1 - x^(j^4), {j, 1, 10}]; gser =
    Series[g, {x, 0, 105}]; Table[Coefficient[gser, x, n], {n, 1, 102}] (* Jean-François Alcover, Oct 29 2012, after Emeric Deutsch *)

Formula

G.f.: -1+1/product(1-x^(j^4),j=1..infinity). - Emeric Deutsch, Apr 06 2006
a(n) ~ exp(5 * (Gamma(1/4)*Zeta(5/4))^(4/5) * n^(1/5) / 2^(16/5)) * (Gamma(1/4)*Zeta(5/4))^(4/5) / (2^(47/10) * sqrt(5) * Pi^(5/2) * n^(13/10)) [Hardy & Ramanujan, 1917]. - Vaclav Kotesovec, Dec 29 2016
G.f.: Sum_{i>=1} x^(i^4) / Product_{j=1..i} (1 - x^(j^4)). - Ilya Gutkovskiy, May 07 2017

A099591 Numbers that are the sum of no fewer than 17 biquadrates (4th powers).

Original entry on oeis.org

47, 62, 63, 77, 78, 79, 127, 142, 143, 157, 158, 159, 207, 222, 223, 237, 238, 239, 287, 302, 303, 317, 318, 319, 367, 382, 383, 397, 398, 399, 447, 462, 463, 477, 478, 479, 527, 542, 543, 557, 558, 559, 607, 622, 623, 687, 702, 703, 752, 767, 782, 783
Offset: 1

Views

Author

Ralf Stephan, Oct 25 2004

Keywords

Comments

There are 96 members in the sequence, the largest being 13792, see the Deshouillers et al. references.

Examples

			62 is the sum of 17 4th powers and no fewer, so 62 is a member.
63 is the sum of 18 4th powers and no fewer, so 63 is a member, although it is not a member of A046048.
		

Crossrefs

Programs

  • Mathematica
    f[n_] := f[n] = (k = 0; While[k++; PowersRepresentations[n, k, 4] == {}]; k); Select[Range[800], f[#] >= 17 &] (* Jean-François Alcover, Sep 02 2011 *)

Extensions

a(25) changed from 368 to 367 by T. D. Noe, Sep 07 2006

A079611 Waring's problem: conjectured values for G(n), the smallest number m such that every sufficiently large number is the sum of at most m n-th powers of positive integers.

Original entry on oeis.org

1, 4, 4, 16, 6, 9, 8, 32, 13, 12, 12, 16, 14, 15, 16, 64, 18, 27, 20, 25
Offset: 1

Views

Author

N. J. A. Sloane, Jan 28 2003

Keywords

Comments

The only certain values are G(1) = 1, G(2) = 4 and G(4) = 16.
See A002804 for the simpler problem of Waring's original conjecture, which does not restrict the bound to "sufficiently large" numbers. - M. F. Hasler, Jun 29 2014

Examples

			It is known that every sufficiently large number is the sum of 16 fourth powers, and 16 is the smallest number with this property, so a(4) = G(4) = 16. (The numbers 16^k*31 are not the sum of fewer than 16 fourth powers.)
		

References

  • G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 5th ed., Oxford Univ. Press, 1979, th. 395 (shows G(4) >= 16).
  • R. C. Vaughan and T. D. Wooley, Waring's problem: a survey, pp. 285-324 of Surveys in Number Theory (Urbana, May 21, 2000), ed. M. A. Bennett et al., Peters, 2003.

Crossrefs

Extensions

Entry revised Jun 29 2014

A046044 Sum of 13 but no fewer nonzero fourth powers.

Original entry on oeis.org

13, 28, 43, 58, 73, 93, 108, 123, 138, 153, 173, 188, 203, 208, 218, 233, 253, 268, 283, 298, 313, 333, 348, 363, 378, 393, 413, 428, 443, 448, 458, 473, 493, 508, 523, 538, 553, 573, 588, 603, 618, 637, 653, 668, 683, 688, 698, 717, 733, 748, 763, 778, 797
Offset: 1

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Keywords

Crossrefs

Programs

  • Mathematica
    isSumQ[n_] := Do[pr = PowersRepresentations[n, k, 4]; If[k < 13, If[pr != {} , Return[False]], If[k == 13 && pr != {}, Return[True], Return[False]]], {k, 1, 13}]; Reap[For[n = 1, n <= 800, n++, If[isSumQ[n], Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Oct 25 2012 *)

Extensions

More terms from Arlin Anderson (starship1(AT)gmail.com)

A046048 Numbers that are the sum of 17 but no fewer nonzero fourth powers.

Original entry on oeis.org

47, 62, 77, 127, 142, 157, 207, 222, 237, 287, 302, 317, 367, 382, 397, 447, 462, 477, 527, 542, 557, 607, 622, 687, 702, 752, 767, 782, 847, 862, 927, 942, 992, 1007, 1022, 1087, 1102, 1167, 1182, 1232, 1247, 1327, 1407, 1487, 1567, 1647, 1727, 1807, 2032
Offset: 1

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Author

Keywords

Comments

a(65) = 13792 is the last term of this sequence; see A099591 for further references.

Examples

			62 is the sum of 17 4th powers and no fewer, so 62 is a term.
63 is the sum of 18 4th powers and no fewer, so 63 is not a term, although it is a term of A099591.
		

Crossrefs

Programs

  • Mathematica
    lim = 2100; f[n_] := f[n] = (k = 0; While[k++; k <= 17 && PowersRepresentations[n, k, 4] == {}]; k); Select[Range[lim], f[#] == 17 &] (* Jean-François Alcover, Sep 08 2011 *)

Extensions

More terms from Arlin Anderson (starship1(AT)gmail.com)

A046045 Sum of 14 but no fewer nonzero fourth powers.

Original entry on oeis.org

14, 29, 44, 59, 74, 94, 109, 124, 139, 154, 174, 189, 204, 219, 224, 234, 254, 269, 284, 299, 314, 334, 349, 364, 379, 394, 414, 429, 444, 459, 464, 474, 494, 509, 524, 539, 554, 574, 589, 604, 619, 638, 654, 669, 684, 699, 704, 718, 734, 749, 764, 779, 798
Offset: 1

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Author

Keywords

Crossrefs

Extensions

More terms from Arlin Anderson (starship1(AT)gmail.com)

A047714 Sums of 3 but no fewer nonzero fourth powers.

Original entry on oeis.org

3, 18, 33, 48, 83, 98, 113, 163, 178, 243, 258, 273, 288, 338, 353, 418, 513, 528, 593, 627, 642, 657, 707, 722, 768, 787, 882, 897, 962, 1137, 1251, 1266, 1298, 1313, 1328, 1331, 1378, 1393, 1458, 1506, 1553, 1568, 1633, 1808, 1875, 1922, 1937, 2002, 2177
Offset: 1

Views

Author

Arlin Anderson (starship1(AT)gmail.com)

Keywords

Comments

Identical to A003337 for n = 1..87. - Michael S. Branicky, Mar 18 2021

Crossrefs

Subsequence of A003337.

Programs

  • Maple
    N:= 3000: # for terms <= N
    F1:= {seq(i^4,i=1..floor(N^(1/4)))}: n1:= nops(F1):
    F2:= select(`<=`,{seq(seq(F1[i]+F1[j],i=1..j),j=1..nops(F1))},N):
    F3:= select(`<=`,{seq(seq(s+t,s=F1),t=F2)},N):
    A:= sort(convert(F3 minus (F2 union F1), list)); # Robert Israel, Jul 24 2020
  • Python
    def aupto(lim):
      p1 = set(i**4 for i in range(1, int(lim**.25)+2) if i**4 <= lim)
      p2 = set(a+b for a in p1 for b in p1 if a+b <= lim)
      p3 = set(apb+c for apb in p2 for c in p1 if apb+c <= lim)
      return sorted(p3-p2-p1)
    print(aupto(2400)) # Michael S. Branicky, Mar 18 2021

Formula

A002377(a(n)) = 3. - Robert Israel, Jul 24 2020
Equals A003337 - A344187 - A000583. - Sean A. Irvine, May 15 2021

A046046 Sum of 15 but no fewer nonzero fourth powers.

Original entry on oeis.org

15, 30, 45, 60, 75, 95, 110, 125, 140, 155, 175, 190, 205, 220, 235, 240, 255, 270, 285, 300, 315, 335, 350, 365, 380, 395, 415, 430, 445, 460, 475, 480, 495, 510, 525, 540, 555, 575, 590, 605, 620, 639, 655, 670, 685, 700, 719, 720, 735, 750, 765, 780, 799
Offset: 1

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Author

Keywords

Crossrefs

Extensions

More terms from Arlin Anderson (starship1(AT)gmail.com)
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