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.

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A048930 Numbers that are the sum of 6 positive cubes in exactly 2 ways.

Original entry on oeis.org

158, 165, 184, 228, 235, 247, 256, 261, 268, 273, 275, 280, 282, 284, 287, 291, 294, 306, 310, 313, 317, 324, 331, 332, 343, 345, 347, 350, 352, 362, 371, 373, 376, 378, 380, 385, 387, 388, 392, 395, 399, 404, 406, 408, 418, 425, 430, 432, 436, 437, 441
Offset: 1

Views

Author

Keywords

Comments

It appears that this sequence has 1094 terms, the last of which is 21722. - Donovan Johnson, Jan 09 2013

Examples

			158 is in the sequence since 158 = 64+64+27+1+1+1 = 125+8+8+8+8+1.
		

Crossrefs

Programs

  • Mathematica
    Reap[For[n = 1, n <= 500, n++, pr = Select[ PowersRepresentations[n, 6, 3], Times @@ # != 0 &]; If[pr != {} && Length[pr] == 2, Print[n, pr]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Jul 31 2013 *)
  • PARI
    mx=10^6; ct=vector(mx); cb=vector(99); for(i=1, 99, cb[i]=i^3); for(i1=1, 99, s1=cb[i1]; for(i2=i1, 99, s2=s1+cb[i2]; if(s2+4*cb[i2]>mx, next(2)); for(i3=i2, 99, s3=s2+cb[i3]; if(s3+3*cb[i3]>mx, next(2)); for(i4=i3, 99, s4=s3+cb[i4]; if(s4+2*cb[i4]>mx, next(2)); for(i5=i4, 99, s5=s4+cb[i5]; if(s5+cb[i5]>mx, next(2)); for(i6=i5, 99, s6=s5+cb[i6]; if(s6>mx, next(2)); ct[s6]++)))))); n=0; for(i=6, mx, if(ct[i]==2, n++; write("b048930.txt", n " " i))) /* Donovan Johnson, Jan 09 2013 */

Extensions

Terms corrected by Donovan Johnson, Jan 09 2013

A048931 Numbers that are the sum of 6 positive cubes in exactly 3 ways.

Original entry on oeis.org

221, 254, 369, 411, 443, 469, 495, 502, 576, 595, 600, 648, 658, 684, 704, 711, 720, 739, 746, 753, 760, 765, 767, 772, 774, 779, 786, 793, 811, 818, 828, 835, 844, 854, 863, 866, 874, 880, 884, 886, 892, 893, 899, 905, 910, 919, 928, 929, 935, 936, 937
Offset: 1

Views

Author

Keywords

Comments

It appears that this sequence has 1141 terms, the last of which is 26132. - Donovan Johnson, Jan 09 2013

Examples

			221 is in the sequence since 221 = 216+1+1+1+1+1 = 125+64+8+8+8+8 = 64+64+64+27+1+1.
		

Crossrefs

Programs

  • Mathematica
    Reap[For[n = 1, n <= 1000, n++, pr = Select[ PowersRepresentations[n, 6, 3], Times @@ # != 0 &]; If[pr != {} && Length[pr] == 3, Print[n, pr]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Jul 31 2013 *)
  • PARI
    mx=10^6; ct=vector(mx); cb=vector(99); for(i=1, 99, cb[i]=i^3); for(i1=1, 99, s1=cb[i1]; for(i2=i1, 99, s2=s1+cb[i2]; if(s2+4*cb[i2]>mx, next(2)); for(i3=i2, 99, s3=s2+cb[i3]; if(s3+3*cb[i3]>mx, next(2)); for(i4=i3, 99, s4=s3+cb[i4]; if(s4+2*cb[i4]>mx, next(2)); for(i5=i4, 99, s5=s4+cb[i5]; if(s5+cb[i5]>mx, next(2)); for(i6=i5, 99, s6=s5+cb[i6]; if(s6>mx, next(2)); ct[s6]++)))))); n=0; for(i=6, mx, if(ct[i]==3, n++; write("b048931.txt", n " " i))) /* Donovan Johnson, Jan 09 2013 */

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Oct 02 2000

A048929 Numbers that are the sum of 6 positive cubes in exactly 1 way.

Original entry on oeis.org

6, 13, 20, 27, 32, 34, 39, 41, 46, 48, 53, 58, 60, 65, 67, 69, 72, 76, 79, 83, 84, 86, 90, 91, 95, 97, 98, 102, 104, 105, 109, 110, 116, 117, 121, 123, 124, 128, 130, 132, 135, 136, 137, 139, 142, 143, 144, 146, 147, 151, 153, 154, 156, 160, 161, 162, 163, 170
Offset: 1

Views

Author

Keywords

Comments

It appears that this sequence has 841 terms, the last of which is 19417. This means that all numbers greater than 19417 can be written as the sum of six positive cubes in at least two ways. - T. D. Noe, Dec 13 2006

Crossrefs

Cf. A057907 (numbers not the sum of six positive cubes)

Programs

  • Mathematica
    Select[ Range[200], Length[ Select[ PowersRepresentations[#, 6, 3], And @@ (Positive /@ #) &]] == 1 &] (* Jean-François Alcover, Oct 25 2012 *)
  • Python
    from collections import Counter
    from itertools import combinations_with_replacement as multi_combs
    def aupto(lim):
      c = filter(lambda x: x<=lim, (i**3 for i in range(1, int(lim**(1/3))+2)))
      s = filter(lambda x: x<=lim, (sum(mc) for mc in multi_combs(c, 6)))
      counts = Counter(s)
      return sorted(k for k in counts if counts[k]==1)
    print(aupto(20000)) # Michael S. Branicky, Jun 13 2021

A345511 Numbers that are the sum of six cubes in two or more ways.

Original entry on oeis.org

158, 165, 184, 221, 228, 235, 247, 254, 256, 261, 268, 273, 275, 280, 282, 284, 287, 291, 294, 306, 310, 313, 317, 324, 331, 332, 343, 345, 347, 350, 352, 362, 369, 371, 373, 376, 378, 380, 385, 387, 388, 392, 395, 399, 404, 406, 408, 411, 418, 425, 430, 432
Offset: 1

Views

Author

David Consiglio, Jr., Jun 20 2021

Keywords

Crossrefs

Programs

  • Python
    from itertools import combinations_with_replacement as cwr
    from collections import defaultdict
    keep = defaultdict(lambda: 0)
    power_terms = [x**3 for x in range(1, 1000)]
    for pos in cwr(power_terms, 6):
        tot = sum(pos)
        keep[tot] += 1
        rets = sorted([k for k, v in keep.items() if v >= 2])
        for x in range(len(rets)):
            print(rets[x])

A057907 Positive integers that are not the sum of precisely six positive cubes.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 33, 35, 36, 37, 38, 40, 42, 43, 44, 45, 47, 49, 50, 51, 52, 54, 55, 56, 57, 59, 61, 62, 63, 64, 66, 68, 70, 71, 73, 74, 75, 77, 78, 80, 81, 82, 85, 87, 88, 89, 92, 93, 94, 96
Offset: 1

Views

Author

Keywords

Comments

It appears that this sequence has 492 terms, the last of which is 19202. - T. D. Noe, Dec 13 2006

Crossrefs

Numbers not in (complement of) A003329.
Cf. A048929 (numbers that are the sum of six positive cubes in exactly 1 way).

Programs

  • Mathematica
    Select[ Range[100], Length[ Select[ PowersRepresentations[#, 6, 3], And @@ (Positive /@ #) &]] != 1 &] (* Jean-François Alcover, Oct 25 2012 *)

A003386 Numbers that are the sum of 8 nonzero 8th powers.

Original entry on oeis.org

8, 263, 518, 773, 1028, 1283, 1538, 1793, 2048, 6568, 6823, 7078, 7333, 7588, 7843, 8098, 8353, 13128, 13383, 13638, 13893, 14148, 14403, 14658, 19688, 19943, 20198, 20453, 20708, 20963, 26248, 26503, 26758, 27013, 27268, 32808, 33063, 33318, 33573
Offset: 1

Views

Author

Keywords

Comments

As the order of addition doesn't matter we can assume terms are in nondecreasing order. - David A. Corneth, Aug 01 2020

Examples

			From _David A. Corneth_, Aug 01 2020: (Start)
9534597 is in the sequence as 9534597 = 2^8 + 3^8 + 3^8 + 3^8 + 5^8 + 6^8 + 6^8 + 7^8.
13209988 is in the sequence as 13209988 = 1^8 + 1^8 + 2^8 + 2^8 + 2^8 + 6^8 + 7^8 + 7^8.
19046628 is in the sequence as 19046628 = 2^8 + 2^8 + 3^8 + 4^8 + 6^8 + 7^8 + 7^8 + 7^8. (End)
		

Crossrefs

A###### (x, y): Numbers that are the form of x nonzero y-th powers.
Cf. A000404 (2, 2), A000408 (3, 2), A000414 (4, 2), A003072 (3, 3), A003325 (3, 2), A003327 (4, 3), A003328 (5, 3), A003329 (6, 3), A003330 (7, 3), A003331 (8, 3), A003332 (9, 3), A003333 (10, 3), A003334 (11, 3), A003335 (12, 3), A003336 (2, 4), A003337 (3, 4), A003338 (4, 4), A003339 (5, 4), A003340 (6, 4), A003341 (7, 4), A003342 (8, 4), A003343 (9, 4), A003344 (10, 4), A003345 (11, 4), A003346 (12, 4), A003347 (2, 5), A003348 (3, 5), A003349 (4, 5), A003350 (5, 5), A003351 (6, 5), A003352 (7, 5), A003353 (8, 5), A003354 (9, 5), A003355 (10, 5), A003356 (11, 5), A003357 (12, 5), A003358 (2, 6), A003359 (3, 6), A003360 (4, 6), A003361 (5, 6), A003362 (6, 6), A003363 (7, 6), A003364 (8, 6), A003365 (9, 6), A003366 (10, 6), A003367 (11, 6), A003368 (12, 6), A003369 (2, 7), A003370 (3, 7), A003371 (4, 7), A003372 (5, 7), A003373 (6, 7), A003374 (7, 7), A003375 (8, 7), A003376 (9, 7), A003377 (10, 7), A003378 (11, 7), A003379 (12, 7), A003380 (2, 8), A003381 (3, 8), A003382 (4, 8), A003383 (5, 8), A003384 (6, 8), A003385 (7, 8), A003387 (9, 8), A003388 (10, 8), A003389 (11, 8), A003390 (12, 8), A003391 (2, 9), A003392 (3, 9), A003393 (4, 9), A003394 (5, 9), A003395 (6, 9), A003396 (7, 9), A003397 (8, 9), A003398 (9, 9), A003399 (10, 9), A004800 (11, 9), A004801 (12, 9), A004802 (2, 10), A004803 (3, 10), A004804 (4, 10), A004805 (5, 10), A004806 (6, 10), A004807 (7, 10), A004808 (8, 10), A004809 (9, 10), A004810 (10, 10), A004811 (11, 10), A004812 (12, 10), A004813 (2, 11), A004814 (3, 11), A004815 (4, 11), A004816 (5, 11), A004817 (6, 11), A004818 (7, 11), A004819 (8, 11), A004820 (9, 11), A004821 (10, 11), A004822 (11, 11), A004823 (12, 11), A047700 (5, 2).

Programs

  • Mathematica
    M = 92646056; m = M^(1/8) // Ceiling; Reap[
    For[a = 1, a <= m, a++, For[b = a, b <= m, b++, For[c = b, c <= m, c++,
    For[d = c, d <= m, d++, For[e = d, e <= m, e++, For[f = e, f <= m, f++,
    For[g = f, g <= m, g++, For[h = g, h <= m, h++,
    s = a^8 + b^8 + c^8 + d^8 + e^8 + f^8 + g^8 + h^8;
    If[s <= M, Sow[s]]]]]]]]]]][[2, 1]] // Union (* Jean-François Alcover, Dec 01 2020 *)

Extensions

b-file checked by R. J. Mathar, Aug 01 2020
Incorrect program removed by David A. Corneth, Aug 01 2020

A344805 Numbers that are the sum of six squares in one or more ways.

Original entry on oeis.org

6, 9, 12, 14, 15, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77
Offset: 1

Views

Author

David Consiglio, Jr., Jun 19 2021

Keywords

Examples

			9 is a term because 9 = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 2^2.
		

Crossrefs

Programs

  • Python
    from itertools import combinations_with_replacement as cwr
    from collections import defaultdict
    keep = defaultdict(lambda: 0)
    power_terms = [x**2 for x in range(1, 1000)]
    for pos in cwr(power_terms, 6):
        tot = sum(pos)
        keep[tot] += 1
        rets = sorted([k for k, v in keep.items() if v >= 1])
        for x in range(len(rets)):
            print(rets[x])

Formula

From Chai Wah Wu, Jun 12 2025: (Start)
All integers >= 20 are terms. See A345508 for a similar proof.
a(n) = 2*a(n-1) - a(n-2) for n > 9.
G.f.: x*(-x^8 + x^7 - x^6 + x^5 - x^4 - x^3 - 3*x + 6)/(x - 1)^2. (End)

A025459 Number of partitions of n into 6 positive cubes.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Maple
    A025459 := proc(n)
        local a,x,y,z,u,v,wcu ;
        a := 0 ;
        for x from 1 do
            if 6*x^3 > n then
                return a;
            end if;
            for y from x do
                if x^3+5*y^3 > n then
                    break;
                end if;
                for z from y do
                    if x^3+y^3+4*z^3 > n then
                        break;
                    end if;
                    for u from z do
                        if x^3+y^3+z^3+3*u^3 > n then
                            break;
                        end if;
                        for v from u do
                            if x^3+y^3+z^3+u^3+2*v^3 > n then
                                break;
                            end if;
                            wcu := n-x^3-y^3-z^3-u^3-v^3 ;
                            if isA000578(wcu) then
                                a := a+1 ;
                            end if;
                        end do:
                    end do:
                end do:
            end do:
        end do:
    end proc: # R. J. Mathar, Sep 15 2015
    # Alternative:
    N:= 200:
    G:= mul(1/(1-y*x^(k^3)),k=1..floor(N^(1/3))):
    C6:= coeff(series(G,y,7),y,6):
    S:= series(C6,x,N+1):
    seq(coeff(S,x,i),i=0..N); # Robert Israel, May 10 2020
  • Mathematica
    a[n_] := Count[PowersRepresentations[n, 6, 3], pr_List /; FreeQ[pr, 0]];
    a /@ Range[0, 200] (* Jean-François Alcover, Jun 22 2020 *)
    Table[Count[IntegerPartitions[n,{6}],?(AllTrue[Surd[#,3],IntegerQ]&)],{n,0,110}] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale, Jun 06 2021 *)

Formula

a(n) = [x^n y^6] Product_{k>=1} 1/(1 - y*x^(k^3)). - Ilya Gutkovskiy, Apr 23 2019

A069137 Numbers which are sums of neither 1, 2, 3, 4, 5 or 6 nonnegative cubes.

Original entry on oeis.org

7, 14, 15, 21, 22, 23, 42, 47, 49, 50, 61, 77, 85, 87, 103, 106, 111, 112, 113, 114, 122, 140, 148, 159, 166, 167, 174, 175, 178, 185, 186, 204, 211, 212, 223, 229, 230, 231, 237, 238, 239, 276, 292, 295, 300, 302, 303, 311, 327, 329, 337, 340, 356, 363, 364
Offset: 1

Views

Author

N. J. A. Sloane, Apr 08 2002; edited Sep 15 2006

Keywords

Comments

Sequence is conjectured to be finite.

Examples

			Numbers which need at least seven terms to represent them as a sum of positive cubes: 14=8+1+1+1+1+1+1.
		

References

  • Bohman, Jan and Froberg, Carl-Erik; Numerical investigation of Waring's problem for cubes, Nordisk Tidskr. Informationsbehandling (BIT) 21 (1981), 118-122.
  • F. Romani, Computations concerning Waring's problem, Calcolo, 19 (1982), 415-431.

Crossrefs

Formula

Natural numbers remaining if union of A003325, A003072, A003327, A003328, A003329 and A000578 sets were deleted. Remark: this sequence itself does not include cubes, in contrast to A085334.

A122730 Primes that are the sum of 6 positive cubes.

Original entry on oeis.org

13, 41, 53, 67, 79, 83, 97, 109, 137, 139, 151, 163, 173, 179, 191, 193, 199, 233, 241, 263, 271, 277, 313, 317, 331, 347, 359, 373, 383, 389, 397, 421, 433, 439, 443, 449, 457, 463, 467, 479, 499, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593
Offset: 1

Views

Author

Jonathan Vos Post, Sep 23 2006

Keywords

Comments

By parity, there must be an odd number of odds in the sum. Hence this sequence is the union of primes which are the sum of an even and five odd cubes (such as x1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 2^3); primes which are the sum of the cube of three even numbers and the cubes of three odd numbers (such as 53 = 1^3 + 1^3 + 2^3 + 2^3 + 2^3 + 3^3); and the primes which are the sum of the cube of an odd number and the cubes of five even numbers (such as 1^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 or 67 = 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 3^3). A subset of this sequence is the primes which are the sum of the cubes of six distinct primes (i.e. of the form 2^3 + p^3 + q^3 + r^3 + s^3 + t^3 for p, q, r, s, t distinct odd primes) such as 8693 = 2^3 + 3^3 + 5^3 + 7^3 + 11^3 + 19^3. Another subsequence is the primes which are the sum of six cubes in two different ways, such as 313 = 1^3 + 2^3 + 3^3 + 3^3 + 5^3 + 5^3 = 2^3 + 2^3 + 3^3 + 3^3 + 3^3 + 6^3. Similarly, another subsequence is the primes which are the sum of six cubes in three different ways, such as 443. No prime can be the sum of two cubes (by factorization of the sum of two cubes).

Examples

			a(1) = 13 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 2^3.
a(2) = 41 = 1^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3
a(3) = 53 = 1^3 + 1^3 + 2^3 + 2^3 + 2^3 + 3^3.
a(4) = 67 = 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 3^3.
		

Crossrefs

Programs

  • Mathematica
    up = 900; q = Range[up^(1/3)]^3; a = {0}; Do[ b = Select[ Union@ Flatten@ Table[e + a, {e, q}], # <= up &]; a = b, {k, 6}]; Select[a, PrimeQ] (* Giovanni Resta, Jun 13 2016 *)

Formula

A000040 INTERSECTION A003329.

Extensions

a(13)-a(53) from Giovanni Resta, Jun 13 2016
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