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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A165210 Primes of the form (6^m - 1)/5.

Original entry on oeis.org

7, 43, 55987, 7369130657357778596659, 3546245297457217493590449191748546458005595187661976371
Offset: 1

Views

Author

Rick L. Shepherd, Sep 07 2009

Keywords

Comments

Prime repunits in base 6 whose representation consists of m 1's. The exponents m are in A004062. a(5) and a(6) have 55 and 99 decimal digits, respectively.

Examples

			a(2) = (6^A004062(2) - 1)/5 = (6^3 - 1)/5 = 215/5 = 43, which is 111_6.
		

Crossrefs

Programs

  • Magma
    [a: n in [1..200] | IsPrime(a) where a is  (6^n-1) div 5 ]; // Vincenzo Librandi, Dec 09 2011
  • Mathematica
    Select[Table[(6^n-1)/5, {n,0,2000}], PrimeQ] (* Vincenzo Librandi, Dec 09 2011 *)

Formula

a(n) = (6^A004062(n) - 1)/5.

A218728 a(n) = (25^n - 1)/24.

Original entry on oeis.org

0, 1, 26, 651, 16276, 406901, 10172526, 254313151, 6357828776, 158945719401, 3973642985026, 99341074625651, 2483526865641276, 62088171641031901, 1552204291025797526, 38805107275644938151, 970127681891123453776, 24253192047278086344401, 606329801181952158610026
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 25 (A009969); q-integers for q=25.
Partial sums are in A014914. Also, the sequence is related to A014943 by A014943(n) = n*a(n) - Sum_{i=0..n-1} a(i) for n > 0. - Bruno Berselli, Nov 07 2012

Crossrefs

Programs

Formula

a(n) = floor(25^n/24).
From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1-x)*(1-25*x)).
a(n) = 26*a(n-1) - 25*a(n-2). (End)
E.g.f.: exp(13*x)*sinh(12*x)/12. - Elmo R. Oliveira, Aug 27 2024
a(n) = 25*a(n-1) + 1. - Jerzy R Borysowicz, Sep 05 2025

A218743 a(n) = (40^n - 1)/39.

Original entry on oeis.org

0, 1, 41, 1641, 65641, 2625641, 105025641, 4201025641, 168041025641, 6721641025641, 268865641025641, 10754625641025641, 430185025641025641, 17207401025641025641, 688296041025641025641, 27531841641025641025641, 1101273665641025641025641, 44050946625641025641025641
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 40 (A009983).

Crossrefs

Programs

  • Magma
    [n le 2 select n-1 else 41*Self(n-1) - 40*Self(n-2): n in [1..20]]; // Vincenzo Librandi, Nov 07 2012
  • Mathematica
    LinearRecurrence[{41, -40}, {0, 1}, 30] (* Vincenzo Librandi, Nov 07 2012 *)
  • Maxima
    A218743(n):=floor(40^n/39)$ makelist(A218743(n),n,0,30); /* Martin Ettl, Nov 05 2012 */
    
  • PARI
    a(n)=40^n\39
    

Formula

a(n) = floor(40^n/39).
From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1-x)*(1-40*x)).
a(n) = 41*a(n-1) - 40*a(n-2). (End)
E.g.f.: exp(x)*(exp(39*x) - 1)/39. - Elmo R. Oliveira, Aug 29 2024

A269025 a(n) = Sum_{k = 0..n} 60^k.

Original entry on oeis.org

1, 61, 3661, 219661, 13179661, 790779661, 47446779661, 2846806779661, 170808406779661, 10248504406779661, 614910264406779661, 36894615864406779661, 2213676951864406779661, 132820617111864406779661, 7969237026711864406779661, 478154221602711864406779661
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 18 2016

Keywords

Comments

Partial sums of powers of 60 (A159991).
Converges in a 10-adic sense to ...762711864406779661.
More generally, the ordinary generating function for the Sum_{k = 0..n} m^k is 1/((1 - m*x)*(1 - x)). Also, Sum_{k = 0..n} m^k = (m^(n + 1) - 1)/(m - 1).

Crossrefs

Cf. A159991.
Cf. similar sequences of the form (k^n-1)/(k-1): A000225 (k=2), A003462 (k=3), A002450 (k=4), A003463 (k=5), A003464 (k=6), A023000 (k=7), A023001 (k=8), A002452 (k=9), A002275 (k=10), A016123 (k=11), A016125 (k=12), A091030 (k=13), A135519 (k=14), A135518 (k=15), A131865 (k=16), A091045 (k=17), A218721 (k=18), A218722 (k=19), A064108 (k=20), A218724-A218734 (k=21..31), A132469 (k=32), A218736-A218753 (k=33..50), this sequence (k=60), A133853 (k=64), A094028 (k=100), A218723 (k=256), A261544 (k=1000).

Programs

  • Mathematica
    Table[Sum[60^k, {k, 0, n}], {n, 0, 15}]
    Table[(60^(n + 1) - 1)/59, {n, 0, 15}]
    LinearRecurrence[{61, -60}, {1, 61}, 15]
  • PARI
    a(n)=60^n + 60^n\59 \\ Charles R Greathouse IV, Jul 26 2016

Formula

G.f.: 1/((1 - 60*x)*(1 - x)).
a(n) = (60^(n + 1) - 1)/59 = 60^n + floor(60^n/59).
a(n+1) = 60*a(n) + 1, a(0)=1.
a(n) = Sum_{k = 0..n} A159991(k).
Sum_{n>=0} 1/a(n) = 1.016671221665660580331...
E.g.f.: exp(x)*(60*exp(59*x) - 1)/59. - Stefano Spezia, Mar 23 2023

A016244 Expansion of 1/((1-x)*(1-6*x)*(1-9*x)).

Original entry on oeis.org

1, 16, 187, 1942, 19033, 180628, 1681639, 15470674, 141251605, 1283357680, 11622778531, 105040363246, 947975408017, 8547451504972, 77021100541663, 693754126856458, 6247172473597069, 56244864253707304
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(1 -96*6^n +135*9^n)/40: n in [0..40]]; // G. C. Greubel, Jan 30 2022
    
  • Mathematica
    LinearRecurrence[{16,-69,54}, {1,16,187}, 41] (* G. C. Greubel, Jan 30 2022 *)
  • PARI
    Vec(1/((1-x)*(1-6*x)*(1-9*x)) + O(x^40)) \\ Michel Marcus, Sep 04 2017
    
  • Sage
    [(1 -16*6^(n+1) +15*9^(n+1))/40 for n in (0..40)] #  G. C. Greubel, Jan 30 2022

Formula

a(n) = (1 - 96*6^n + 135*9^n)/40. - Neven Juric, Oct 22 2009
a(0)=1, a(1)=16, a(n) = 15*a(n-1) - 54*a(n-2) + 1. - Vincenzo Librandi, Feb 10 2011
E.g.f.: (1/40)*(exp(x) - 96*exp(6*x) + 135*exp(9*x)). - G. C. Greubel, Jan 30 2022

A024347 Expansion of 1/((1-x)*(1-6*x)*(1-9*x)*(1-12*x)).

Original entry on oeis.org

1, 28, 523, 8218, 117649, 1592416, 20790631, 264958246, 3320750557, 41132364364, 505211150899, 6167574174034, 74958865496425, 908053837462072, 10973667150086527, 132377759927894782, 1594780291608334453
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-6*x)*(1-9*x)*(1-12*x)))); // Vincenzo Librandi, Jul 16 2013
    
  • Magma
    I:=[1, 28, 523, 8218]; [n le 4 select I[n] else 28*Self(n-1)-261*Self(n-2)+882*Self(n-3)-648*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Jul 16 2013
    
  • Maple
    A024347:= n -> (20*12^(n+3) - 55*9^(n+3) + 44*6^(n+3) -9)/3960; seq(A024347(n), n=0..20); # G. C. Greubel, Jan 30 2022
  • Mathematica
    CoefficientList[Series[1/((1-x)(1-6x)(1-9x)(1-12x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 16 2013 *)
  • PARI
    Vec(1/((1-x)*(1-6*x)*(1-9*x)*(1-12*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
    
  • Sage
    [(20*12^(n+3) - 55*9^(n+3) + 44*6^(n+3) -9)/3960 for n in (0..20)] # G. C. Greubel, Jan 30 2022

Formula

a(n) = (20*12^(n+3) - 55*9^(n+3) + 44*6^(n+3) - 9)/3960. - Yahia Kahloune, Jun 28 2013
a(n) = 28*a(n-1) - 261*a(n-2) + 882*a(n-3) - 648*a(n-4) for n > 3; a(0)=1, a(1)=28, a(2)=523, a(3)=8218. - Vincenzo Librandi, Jul 16 2013
E.g.f.: (-9*exp(x) + 9504*exp(6*x) - 40095*exp(9*x) + 34560*exp(12*x))/3960. - G. C. Greubel, Jan 30 2022

A218725 a(n) = (22^n - 1)/21.

Original entry on oeis.org

0, 1, 23, 507, 11155, 245411, 5399043, 118778947, 2613136835, 57489010371, 1264758228163, 27824681019587, 612142982430915, 13467145613480131, 296277203496562883, 6518098476924383427, 143398166492336435395, 3154759662831401578691, 69404712582290834731203
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 22; q-integers for q=22: Diagonal k=1 in the triangle A022186.
Partial sums are in A014907. Also, the sequence is related to A014940 by A014940(n) = n*a(n) - Sum_{i=0..n-1} a(i) for n > 0. [Bruno Berselli, Nov 06 2012]

Crossrefs

Programs

Formula

a(n) = floor(22^n/21).
G.f.: x/((1-x)*(1-22*x)). [Bruno Berselli, Nov 06 2012]
a(n) = 23*a(n-1) - 22*a(n-2). - Vincenzo Librandi, Nov 07 2012
E.g.f.: exp(x)*(exp(21*x) - 1)/21. - Elmo R. Oliveira, Aug 29 2024

A218737 a(n) = (34^n - 1)/33.

Original entry on oeis.org

0, 1, 35, 1191, 40495, 1376831, 46812255, 1591616671, 54114966815, 1839908871711, 62556901638175, 2126934655697951, 72315778293730335, 2458736461986831391, 83597039707552267295, 2842299350056777088031, 96638177901930420993055, 3285698048665634313763871
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 34 (A009978).

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1 - x)*(1 - 34*x)).
a(n) = 35*a(n-1) - 34*a(n-2).
a(n) = floor(34^n/33). (End)
E.g.f.: exp(x)*(exp(33*x) - 1)/33. - Stefano Spezia, Mar 26 2023

A218738 a(n) = (35^n - 1)/34.

Original entry on oeis.org

0, 1, 36, 1261, 44136, 1544761, 54066636, 1892332261, 66231629136, 2318107019761, 81133745691636, 2839681099207261, 99388838472254136, 3478609346528894761, 121751327128511316636, 4261296449497896082261, 149145375732426362879136, 5220088150634922700769761
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 35 (A009979).

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1 - x)*(1 - 35*x)).
a(n) = 36*a(n-1) - 35*a(n-2).
a(n) = floor(35^n/34). (End)
E.g.f.: exp(x)*(exp(34*x) - 1)/34. - Stefano Spezia, Mar 28 2023

A218745 a(n) = (42^n - 1)/41.

Original entry on oeis.org

0, 1, 43, 1807, 75895, 3187591, 133878823, 5622910567, 236162243815, 9918814240231, 416590198089703, 17496788319767527, 734865109430236135, 30864334596069917671, 1296302053034936542183, 54444686227467334771687, 2286676821553628060410855, 96040426505252378537255911
Offset: 0

Views

Author

M. F. Hasler, Nov 04 2012

Keywords

Comments

Partial sums of powers of 42 (A009986).

Crossrefs

Programs

Formula

From Vincenzo Librandi, Nov 07 2012: (Start)
G.f.: x/((1-x)*(1-42*x)).
a(n) = 43*a(n-1) - 42*a(n-2).
a(n) = floor(42^n/41). (End)
E.g.f.: exp(x)*(exp(41*x) - 1)/41. - Elmo R. Oliveira, Aug 29 2024
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