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 15 results. Next

A061103 Duplicate of A016791.

Original entry on oeis.org

8, 125, 512, 1331, 2744, 4913, 8000, 12167, 17576, 24389, 32768, 42875, 54872, 68921, 85184, 103823, 125000, 148877, 175616, 205379, 238328, 274625, 314432, 357911, 405224, 456533, 512000, 571787, 636056, 704969, 778688, 857375, 941192, 1030301, 1124864
Offset: 1

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A016779 a(n) = (3*n + 1)^3.

Original entry on oeis.org

1, 64, 343, 1000, 2197, 4096, 6859, 10648, 15625, 21952, 29791, 39304, 50653, 64000, 79507, 97336, 117649, 140608, 166375, 195112, 226981, 262144, 300763, 343000, 389017, 438976, 493039, 551368, 614125, 681472, 753571, 830584, 912673, 1000000, 1092727, 1191016
Offset: 0

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Comments

The inverse binomial transform is 1, 63, 216, 162, 0, 0, 0 (0 continued). R. J. Mathar, May 07 2008
Perfect cubes with digital root 1 in base 10. Proof: perfect cubes are one of (3*s)^3, (3*s+1)^3 or (3*s+2)^3. Digital roots of (3*s)^3 are 0, digital roots of (3*s+1)^3 are 1, and digital roots of (3*s+2)^3 are 8, using trinomial expansion and the multiplicative property of digits roots. - R. J. Mathar, Jul 31 2010

Examples

			a(2) = (3*2+1)^3 = 343.
a(6) = (3*6+1)^3 = 6859.
		

References

  • S. R. Finch, Mathematical Constants, Cambridge, 2003, Section 1.6.3.
  • Amarnath Murthy, Fabricating a perfect cube with a given valid digit sum (to be published)

Crossrefs

Programs

Formula

Sum_{n>=0} 1/a(n) = 2*Pi^3 / (81*sqrt(3)) + 13*zeta(3)/27.
O.g.f.: (1 + 60*x + 93*x^2 + 8*x^3)/(1 - x)^4. - R. J. Mathar, May 07 2008
E.g.f.: (1 + 63*x + 108*x^2 + 27*x^3)*exp(x). - Ilya Gutkovskiy, Jun 16 2016
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). - Wesley Ivan Hurt, Oct 02 2020
Sum_{n>=1} (-1)^n/a(n) = A226735. - R. J. Mathar, Feb 07 2024

A016792 a(n) = (3*n+2)^4.

Original entry on oeis.org

16, 625, 4096, 14641, 38416, 83521, 160000, 279841, 456976, 707281, 1048576, 1500625, 2085136, 2825761, 3748096, 4879681, 6250000, 7890481, 9834496, 12117361, 14776336, 17850625, 21381376, 25411681, 29986576, 35153041, 40960000, 47458321, 54700816, 62742241, 71639296
Offset: 0

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Subsequence of A000583.

Programs

Formula

From Ilya Gutkovskiy, Jun 16 2016: (Start)
G.f.: (16 + 545*x + 1131*x^2 + 251*x^3 + x^4)/(1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5). (End)
From Amiram Eldar, Mar 31 2022: (Start)
a(n) = A016789(n)^4 = A016790(n)^2.
Sum_{n>=0} 1/a(n) = PolyGamma(3, 2/3)/486. (End)

A016793 a(n) = (3*n + 2)^5.

Original entry on oeis.org

32, 3125, 32768, 161051, 537824, 1419857, 3200000, 6436343, 11881376, 20511149, 33554432, 52521875, 79235168, 115856201, 164916224, 229345007, 312500000, 418195493, 550731776, 714924299, 916132832, 1160290625, 1453933568, 1804229351, 2219006624, 2706784157, 3276800000
Offset: 0

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Crossrefs

Subsequence of A000584.

Programs

  • Magma
    [(3*n+2)^5 : n in [0..30]]; // Vincenzo Librandi, Sep 29 2011
  • Mathematica
    Table[(3n+2)^5,{n,0,100}] (* Mohammad K. Azarian, Jun 15 2016 *)
    LinearRecurrence[{6,-15,20,-15,6,-1},{32,3125,32768,161051,537824,1419857},30] (* Harvey P. Dale, May 10 2024 *)

Formula

From Ilya Gutkovskiy, Jun 16 2016: (Start)
G.f.: (32 + 2933*x + 14498*x^2 + 10678*x^3 + 1018*x^4 + x^5)/(1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6). (End)
From Amiram Eldar, Mar 31 2022: (Start)
a(n) = A016789(n)^5.
Sum_{n>=0} 1/a(n) = 121*zeta(5)/243 - 2*Pi^5/(729*sqrt(3)). (End)

A016794 a(n) = (3*n + 2)^6.

Original entry on oeis.org

64, 15625, 262144, 1771561, 7529536, 24137569, 64000000, 148035889, 308915776, 594823321, 1073741824, 1838265625, 3010936384, 4750104241, 7256313856, 10779215329, 15625000000, 22164361129, 30840979456, 42180533641, 56800235584, 75418890625, 98867482624, 128100283921
Offset: 0

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Crossrefs

Subsequence of A001014.

Programs

Formula

From Amiram Eldar, Mar 31 2022: (Start)
a(n) = A016789(n)^6 = A016790(n)^3 = A016791(n)^2.
Sum_{n>=0} 1/a(n) = PolyGamma(5, 2/3)/87480. (End)

A118719 Cubes for which the digital root is also a cube.

Original entry on oeis.org

0, 1, 8, 64, 125, 343, 512, 1000, 1331, 2197, 2744, 4096, 4913, 6859, 8000, 10648, 12167, 15625, 17576, 21952, 24389, 29791, 32768, 39304, 42875, 50653, 54872, 64000, 68921, 79507, 85184, 97336, 103823, 117649, 125000, 140608, 148877
Offset: 1

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Author

Luc Stevens (lms022(AT)yahoo.com), May 21 2006

Keywords

Comments

All cubes have a digital root 1,8 or 9. (except for the number 0) So this sequence contains all cubes with a digital root which is not 9.
This sequence is 0 union A016779 union A016791.

Examples

			64 is in the sequence because (1) it is a cube and (2) the digital root 1 is also a cube.
		

Crossrefs

Programs

  • Magma
    [0] cat [(6*n+(-1)^n-9)^3 div 64: n in [2..37]];  // Bruno Berselli, May 05 2011
    
  • Mathematica
    Join[{0}, Table[(3*k + {1, 2})^3, {k, 0, 15}] // Flatten] (* Amiram Eldar, Dec 19 2020 *)
  • PARI
    a010888(n)=if(n, (n-1)%9+1)
    lista(nn) = {for (n=0, nn, if (ispower(a010888(n^3), 3), print1(n^3, ", ")););} \\ Michel Marcus, Feb 18 2015

Formula

a(n) = (floor(3*n/2)-2)^3 for n >= 2. - Nathaniel Johnston, May 05 2011
G.f.: x^2*(1+7*x+53*x^2+40*x^3+53*x^4+7*x^5+x^6)/((1+x)^3*(1-x)^4). a(n) = A001651(n-1)^3 for n>1. - Bruno Berselli, May 05 2011
Sum_{n>=2} 1/a(n) = 26*zeta(3)/27. - Amiram Eldar, Dec 19 2020

A016796 a(n) = (3*n + 2)^8.

Original entry on oeis.org

256, 390625, 16777216, 214358881, 1475789056, 6975757441, 25600000000, 78310985281, 208827064576, 500246412961, 1099511627776, 2251875390625, 4347792138496, 7984925229121, 14048223625216, 23811286661761, 39062500000000, 62259690411361, 96717311574016, 146830437604321
Offset: 0

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Crossrefs

Programs

  • Mathematica
    (3 Range[0, 20] + 2)^8 (* Harvey P. Dale, Jan 24 2011 *)

Formula

From Amiram Eldar, Mar 31 2022: (Start)
a(n) = A016789(n)^6 = A016790(n)^3 = A016791(n)^2.
Sum_{n>=0} 1/a(n) = PolyGamma(7, 2/3)/33067440. (End)

A016798 a(n) = (3*n + 2)^10.

Original entry on oeis.org

1024, 9765625, 1073741824, 25937424601, 289254654976, 2015993900449, 10240000000000, 41426511213649, 141167095653376, 420707233300201, 1125899906842624, 2758547353515625, 6278211847988224, 13422659310152401, 27197360938418176, 52599132235830049
Offset: 0

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Programs

Formula

From Harvey P. Dale, Nov 28 2014: (Start)
G.f.: -(1/((x-1)^11))(x^10+1048565*x^9+270940968*x^8+6950443776*x^7+ 43221615834*x^6+86805830970*x^5+61387794480*x^4+14663204952*x^3+ 966376269*x^2+9754361*x+1024).
a(n) = 59049*n^10 + 393660*n^9 + 1180980*n^8 + 2099520*n^7 + 2449440*n^6 + 1959552*n^5 + 1088640*n^4 + 414720*n^3 + 103680*n^2 + 15360*n + 1024. [corrected by Amiram Eldar, Mar 31 2022] (End)
From Amiram Eldar, Mar 31 2022: (Start)
a(n) = A016789(n)^10 = A016790(n)^5 = A016793(n)^2.
Sum_{n>=0} 1/a(n) = PolyGamma(9, 2/3)/21427701120. (End)
a(n) = 11*a(n-1) - 55*a(n-2) + 165*a(n-3) - 330*a(n-4) + 462*a(n-5) - 462*a(n-6) + 330*a(n-7) - 165*a(n-8) + 55*a(n-9) - 11*a(n-10) + a(n-11). - Wesley Ivan Hurt, Dec 31 2023

A016797 a(n) = (3*n + 2)^9.

Original entry on oeis.org

512, 1953125, 134217728, 2357947691, 20661046784, 118587876497, 512000000000, 1801152661463, 5429503678976, 14507145975869, 35184372088832, 78815638671875, 165216101262848, 327381934393961, 618121839509504, 1119130473102767, 1953125000000000, 3299763591802133
Offset: 0

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Crossrefs

Programs

Formula

G.f.: (512 + 1948005*x + 114709518*x^2 + 1103599596*x^3 + 2887100154*x^4 + 2388954618*x^5 + 608260290*x^6 + 37732212*x^7 + 262134*x^8 + x^9)/(1 - x)^10. - Ilya Gutkovskiy, Jun 16 2016
From Amiram Eldar, Mar 31 2022: (Start)
a(n) = A016789(n)^9.
Sum_{n>=0} 1/a(n) = 9841*zeta(9)/19683 - 1618*Pi^9/(55801305*sqrt(3)). (End)

A016799 a(n) = (3*n + 2)^11.

Original entry on oeis.org

2048, 48828125, 8589934592, 285311670611, 4049565169664, 34271896307633, 204800000000000, 952809757913927, 3670344486987776, 12200509765705829, 36028797018963968, 96549157373046875, 238572050223552512, 550329031716248441, 1196683881290399744, 2472159215084012303
Offset: 0

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Programs

Formula

From Amiram Eldar, Apr 01 2022: (Start)
a(n) = A016789(n)^11.
Sum_{n>=0} 1/a(n) = 88573*zeta(11)/177147 - 7388*Pi^11/(2511058725*sqrt(3)). (End)
Showing 1-10 of 15 results. Next