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 1-8 of 8 results.

A024975 Sums of three distinct positive cubes.

Original entry on oeis.org

36, 73, 92, 99, 134, 153, 160, 190, 197, 216, 225, 244, 251, 281, 288, 307, 342, 349, 352, 368, 371, 378, 405, 408, 415, 434, 469, 476, 495, 521, 532, 540, 547, 560, 567, 577, 584, 586, 603, 623, 638, 645, 664, 684, 701, 729, 736, 738, 755, 757, 764, 792, 794, 801, 820
Offset: 1

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Author

Keywords

Comments

Subsequence of A003072. Equals A024973 if duplicates of repeated entries are removed. - R. J. Mathar, Apr 13 2008

Crossrefs

Cf. A122723 (primes in here), A025399-A025402, A025411 (4 distinct positive cubes).

Programs

  • Mathematica
    Total/@Subsets[Range[10]^3,{3}]//Union (* Harvey P. Dale, Aug 22 2021 *)
  • PARI
    list(lim)=my(v=List(),x3,t); lim\=1; for(x=3,sqrtnint(lim-9,3), x3=x^3; for(y=2,min(x-1,sqrtnint(lim-x3-1,3)), t=x3+y^3; for(z=1,min(y-1,sqrtnint(lim-t,3)), listput(v,t+z^3)))); Set(v) \\ Charles R Greathouse IV, Sep 20 2016

Formula

{n: A025469(n) >= 1}. - R. J. Mathar, Jun 15 2018

Extensions

Verified by Don Reble, Nov 19 2006

A137365 Prime numbers n such that n = p1^3 + p2^3 + p3^3, a sum of cubes of 3 distinct prime numbers.

Original entry on oeis.org

1483, 5381, 6271, 7229, 9181, 11897, 13103, 13841, 14489, 17107, 20357, 25747, 26711, 27917, 30161, 30259, 31247, 32579, 36161, 36583, 36677, 36899, 36901, 42083, 48817, 54181, 55511, 55691, 56377, 56897, 57637, 59093, 64151, 66347
Offset: 1

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Keywords

Comments

Numbers n may have multiple decompositions; for example, n=185527 and n=451837 have two, and n=8627527 and n=32816503 have three. The smallest n with more than one decomposition is n = 185527 = 13^3+43^3+47^3 = 19^3+31^3+53^3, the 94th in the sequence. - R. J. Mathar, May 01 2008
Primes in A138853 and A138854. - M. F. Hasler, Apr 13 2008
The least prime, p, which has n decompositions {with its primes} is 1483 = {3, 5, 11}; 185527 = {13, 43, 47} & {19, 31, 53}; 8627527 = {19, 151, 173}, {33, 139, 181} & {71, 73, 199} and 1122871751 = {113, 751, 887}, {131, 701, 919}, {151, 659, 941} & {29, 107, 1039}. - Robert G. Wilson v, May 04 2008
The number of terms < 10^n: 0, 0, 0, 5, 56, 327, 2172, 13417, 86264, 567211, ..., . - Robert G. Wilson v, May 04 2008
The number of decompositions < 10^n: 0, 0, 0, 5, 56, 330, 2201, 13609, 87200, 571770, ..., . - Robert G. Wilson v, May 04 2008

Examples

			1483=3^3+5^3+11^3, 5381=17^3+7^3+5^3, 6271=3^3+11^3+17^3, etc.
		

Crossrefs

Cf. A137366.
Cf. A024975 (a^3+b^3+c^3, a>b>c>0), A122723 (primes in A024975), A138853-A138854.

Programs

  • Maple
    # From R. J. Mathar: (Start)
    isA030078 := proc(n) local cbr; cbr := floor(root[3](n)) ; if cbr^3 = n and isprime(cbr) then true ; else false; fi ; end:
    isA137365 := proc(n) local p1,p2,p3,p3cub ; if isprime(n) then p1 := 2 ; while p1^3 <= n-16 do p2 := nextprime(p1) ; while p1^3+p2^3 <= n-8 do p3cub := n-p1^3-p2^3 ; if p3cub> p2^3 and isA030078(p3cub) then RETURN(true) ; fi ; p2 := nextprime(p2) ; od: p1 := nextprime(p1) ; od; RETURN(false) ; else RETURN(false) ; fi ; end:
    for i from 1 do if isA137365( ithprime(i)) then printf("%d\n",ithprime(i)) ; fi ; od:
    # (End)
  • Mathematica
    Array[r, 99]; Array[y, 99]; For[i = 0, i < 10^2, r[i] = y[i] = 0; i++ ]; z = 4^2; n = 0; For[i1 = 1, i1 < z, a = Prime[i1]; a2 = a^3; For[i2 = i1 + 1, i2 < z, b = Prime[i2]; b2 = b^3; For[i3 = i2 + 1, i3 < z, c = Prime[i3]; c2 = c^3; p = a2 + b2 + c2; If[PrimeQ[p], Print[a2, " + ", b2, " + ", c2, " = ", p]; n++; r[n] = p]; i3++ ]; i2++ ]; i1++ ]; Sort[Array[r, 88]] (* Vladimir Joseph Stephan Orlovsky *)
    lst = {}; Do[p = Prime[q]^3 + Prime[r]^3 + Prime[s]^3; If[PrimeQ@ p, AppendTo[lst, p]], {q, 13}, {r, q - 1}, {s, r - 1}]; Take[Sort@ lst, 36] (* Robert G. Wilson v, Apr 13 2008 *)
    nn=20; lim=Prime[nn]^3+3^3+5^3; Union[Select[Total[#^3]& /@ Subsets[Prime[Range[2,nn]], {3}], #Harvey P. Dale, Jan 15 2011 *)
  • PARI
    c=0; forprime(p=1,10^6, isA138853(p) & write("b137365.txt",c++," ",p)) \\ M. F. Hasler, Apr 13 2008

Formula

A137365 = A000040 intersect A138853 = A000040 intersect A138854. - M. F. Hasler, Apr 13 2008

Extensions

Corrected and extended by Zak Seidov, R. J. Mathar and Robert G. Wilson v, Apr 12 2008
Further edits by R. J. Mathar and N. J. A. Sloane, Jun 07 2008

A306213 Numbers that are the sum of cubes of three distinct positive integers in arithmetic progression.

Original entry on oeis.org

36, 99, 153, 216, 288, 405, 408, 495, 645, 684, 792, 855, 972, 1071, 1197, 1224, 1407, 1548, 1584, 1701, 1728, 1968, 2079, 2241, 2304, 2403, 2541, 2673, 2736, 3051, 3060, 3240, 3264, 3537, 3540, 3888, 3960, 4059, 4131, 4257, 4500, 4587, 4833, 5049, 5160, 5256, 5472, 5643, 5832, 5940, 6336, 6369, 6669
Offset: 1

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Author

Antonio Roldán, Jan 29 2019

Keywords

Comments

Numbers that can be written as 3*a*(a^2 + 2*b^2) = (a-b)^3 + a^3 + (a+b)^3 where 0 < b < a. - Robert Israel, Dec 15 2022

Examples

			153 = 1^3 + 3^3 + 5^3, with 3 - 1 = 5 - 3 = 2;
972 = 3^3 + 6^3 + 9^3, with 6 - 3 = 9 - 6 = 3.
		

Crossrefs

Programs

  • Maple
    N:= 10000: # for terms <= N
    S:= {}:
    for a from 1 while a^3 + (a+1)^3 + (a+2)^3 <= N do
      for d from 1 do
        x:= a^3 + (a+d)^3 + (a+2*d)^3;
        if x > N then break fi;
        S:= S union {x}
    od od:
    sort(convert(S,list)); # Robert Israel, Dec 14 2022
  • PARI
    for(n=3, 7000, k=(n/3)^(1/3); a=2; v=0; while(a<=k&&v==0, b=(n-3*a^3)/(6*a); if(b==truncate(b)&&issquare(b), d=sqrt(b), d=0); if(d>=1&&d<=a-1, v=1; print1(n,", ")); a+=1))
    
  • PARI
    w=List(); for(n=3, 7000, k=(n/3)^(1/3); for(a=2, k, for(c=1, a-1, v=(a-c)^3+a^3+(a+c)^3; if(v==n, listput(w,n))))); print(vecsort(Vec(w),,8))

A180088 Primes which are the sum of three distinct positive cubes in two or more distinct ways.

Original entry on oeis.org

1009, 4229, 4447, 4733, 6301, 7561, 10657, 12377, 12979, 13103, 13859, 14561, 15569, 15667, 17207, 20663, 20747, 20899, 21673, 22511, 24137, 24499, 25999, 27793, 27917, 28001, 28493, 28729, 29917, 31123, 32579, 32833, 32957, 33119
Offset: 1

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Keywords

Comments

1^3+2^3+10^3=1009=4^3+6^3+9^3

Crossrefs

Programs

  • Mathematica
    lst1=Sort@Select[Flatten[Table[a^3+b^3+c^3,{a,1,66},{b,a-1,1,-1},{c,b-1,1,-1}]],PrimeQ[ # ]&]; lst={};Do[If[lst1[[n]]==lst1[[n+1]],AppendTo[lst,lst1[[n]]]],{n,Length[lst1]-1}];lst

A180089 Semiprimes which are the sum of three distinct positive cubes in two or more distinct ways.

Original entry on oeis.org

1366, 1457, 1793, 1945, 3599, 4105, 5435, 7379, 8315, 9017, 10261, 10963, 11773, 12706, 13957, 15163, 15371, 15553, 15751, 15758, 16271, 17263, 17354, 17947, 18649, 19027, 19369, 19657, 19729, 19774, 19781, 19907, 21026, 21167, 22411
Offset: 1

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Keywords

Comments

2^3+3^3+11^3=5^3+8^3+9^3=1366=2*683, 1^3+5^3+11^3=6^3+8^3+9^3=1457=31*47,..

Crossrefs

Programs

  • Mathematica
    f[n_]:=Last/@FactorInteger[n]=={1,1}; lst={};Do[Do[Do[If[f[p=a^3+b^3+c^3],AppendTo[lst,p]],{c,b-1,1,-1}],{b,a-1,1,-1}],{a,55}];lst1=Sort@lst; lst={};Do[If[lst1[[n]]==lst1[[n+1]],AppendTo[lst,lst1[[n]]]],{n,Length[lst1]-1}];lst

A180099 Primes which are the sum of three distinct positive cubes of prime numbers in two or more distinct ways.

Original entry on oeis.org

185527, 451837, 591751, 1265471, 1266929, 1618973, 1626227, 1664713, 2586277, 2754683, 2765519, 2805193, 3422303, 3740309, 3748499, 4154779, 5336479, 5483953, 5557987, 6130151, 6586091, 7231013, 7361801, 7726571, 8205553
Offset: 1

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Examples

			185527 = 47^3+43^3+13^3=53^3+31^3+19^3.
		

Crossrefs

Programs

  • Mathematica
    lst={};Do[Do[Do[If[PrimeQ[p=Prime[a]^3+Prime[b]^3+Prime[c]^3],AppendTo[lst,p]],{c,b-1,1,-1}],{b,a-1,1,-1}],{a,88}];lst1=Sort@lst; lst={};Do[If[lst1[[n]]==lst1[[n+1]],AppendTo[lst,lst1[[n]]]],{n,Length[lst1]-1}];lst
    Select[Tally[Select[Total/@Subsets[Prime[Range[50]]^3,{3}],PrimeQ]],#[[2]]> 1&] [[All,1]]//Sort (* Harvey P. Dale, Sep 26 2020 *)

A385094 Primes that are the sum of distinct positive cubes.

Original entry on oeis.org

73, 197, 251, 281, 307, 349, 379, 433, 443, 503, 521, 541, 547, 577, 587, 631, 659, 673, 701, 709, 719, 757, 821, 827, 829, 853, 863, 881, 883, 919, 947, 953, 1009, 1091, 1097, 1153, 1163, 1171, 1217, 1223, 1231, 1249, 1277, 1289, 1297, 1307, 1361, 1367, 1423, 1433, 1439, 1483, 1493
Offset: 1

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Author

Zhining Yang, Jun 17 2025

Keywords

Comments

12101 is the largest of 421 primes not in this sequence.

Examples

			757 is in the sequence because prime 757 = 1^3 + 3^3 + 9^3 = 1^3 + 2^3 + 4^3 + 5^3 + 6^3 + 7^3.
		

Crossrefs

Programs

  • Mathematica
    m = 15; a = {0}; Do[a = Select[Union[a, a + k^3], # < m^3 &], {k, m}];
    a = Select[PrimeQ]@a

Formula

For n > 1027, a(n) = prime(n + 421).

A180106 Semiprimes which are the sum of three distinct positive cubes of semiprime numbers in two or more distinct ways.

Original entry on oeis.org

88073, 195905, 196057, 196841, 205102, 211466, 610903, 747209, 809966, 1078622, 1543267, 1828441, 1967402, 2143783, 2312029, 2803501, 3055258, 3108673, 3244466, 3477629, 3662567, 4237577, 4770137, 5741074, 5835593, 5908889, 7189265, 7497118, 8438249, 8742781
Offset: 1

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Keywords

Comments

610903 = 74^3+55^3+34^3 = 82^3+39^3+6^3.
88073 = 29*3037 = 21^3+33^3+35^3 = 25^3+26^3+38^3. - Chai Wah Wu, May 20 2017

Crossrefs

Programs

  • Mathematica
    f[n_] := PrimeOmega@ n == 2; lst = {}; Do[Do[Do[If[And[f[a], f[b], f[c], f[p = a^3 + b^3 + c^3]], AppendTo[lst, p]], {c, b - 1, 1, -1}], {b, a - 1, 1, -1}], {a, 200}]; lst1 = Sort@ lst; lst = {}; Do[If[lst1[[n]] == lst1[[n + 1]], AppendTo[lst, lst1[[n]]]], {n, Length[lst1] - 1}]; lst (* Corrected by Michael De Vlieger, May 21 2017 *)

Extensions

Terms corrected by Chai Wah Wu, May 20 2017
Showing 1-8 of 8 results.