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 14 results. Next

A008599 Multiples of 17.

Original entry on oeis.org

0, 17, 34, 51, 68, 85, 102, 119, 136, 153, 170, 187, 204, 221, 238, 255, 272, 289, 306, 323, 340, 357, 374, 391, 408, 425, 442, 459, 476, 493, 510, 527, 544, 561, 578, 595, 612, 629, 646, 663, 680, 697, 714, 731, 748, 765, 782, 799, 816, 833, 850, 867, 884
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

Formula

(floor(a(n)/10) - 5*(a(n) mod 10)) == 0 (mod 17), see A076311. - Reinhard Zumkeller, Oct 06 2002
From Vincenzo Librandi, Dec 24 2010: (Start)
a(n) = 17*n.
a(n) = 2*a(n-1) - a(n-2).
G.f.: 17*x/(x-1)^2. (End)
From Elmo R. Oliveira, Apr 10 2025: (Start)
E.g.f.: 17*x*exp(x).
a(n) = (A008598(n) + A008600(n))/2. (End)

A016850 a(n) = (5*n)^2.

Original entry on oeis.org

0, 25, 100, 225, 400, 625, 900, 1225, 1600, 2025, 2500, 3025, 3600, 4225, 4900, 5625, 6400, 7225, 8100, 9025, 10000, 11025, 12100, 13225, 14400, 15625, 16900, 18225, 19600, 21025, 22500, 24025, 25600, 27225, 28900, 30625, 32400, 34225, 36100, 38025, 40000, 42025
Offset: 0

Views

Author

Keywords

Comments

If we define C(n) = (5*n)^2 (n > 0), the sequence is the first "square-sequence" such that for every n there exists p such that C(n) = C(p) + C(p+n). We observe in fact that p = 3*n because 25 = 3^2 + 4^2. The sequence without 0 is linked with the first nontrivial solution (trivial: n^2 = 0^2 + n^2) of the equation X^2 = 2*Y^2 + 2*n^2 where X = 2*k and Y = 2*p + n which is equivalent to k^2 = p^2 + (p+n)^2 for n given. The second such "square-sequence" is (29*n)^2 (n > 0) because 29^2 = 20^2 + 21^2 and with this relation we obtain (29*n)^2 = (20*n)^2 + (20*n+n)^2. - Richard Choulet, Dec 23 2007

Crossrefs

Cf. A000290, A033429, A053742 (first differences), A008587, A008607.
Similar sequences listed in A244630.

Programs

Formula

a(n) = 25*n^2 = 25*A000290(n) = 5*A033429(n). - Omar E. Pol, Jul 03 2014
From Amiram Eldar, Jan 25 2021: (Start)
Sum_{n>=1} 1/a(n) = Pi^2/150.
Sum_{n>=1} (-1)^(n+1)/a(n) = Pi^2/300.
Product_{n>=1} (1 + 1/a(n)) = sinh(Pi/5)/(Pi/5).
Product_{n>=1} (1 - 1/a(n)) = sin(Pi/5)/(Pi/5) = 5*sqrt((5-sqrt(5))/2)/(2*Pi). (End)
a(n) = Sum_{i=0..n-1} A053742(i). - John Elias, Jun 30 2021
G.f.: 25*x*(1 + x)/(1 - x)^3. - Stefano Spezia, Jul 08 2023
From Elmo R. Oliveira, Nov 30 2024: (Start)
E.g.f.: 25*x*(1 + x)*exp(x).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
a(n) = n*A008607(n) = A000290(A008587(n)) = A008587(n)^2. (End)

A016910 a(n) = (6*n)^2.

Original entry on oeis.org

0, 36, 144, 324, 576, 900, 1296, 1764, 2304, 2916, 3600, 4356, 5184, 6084, 7056, 8100, 9216, 10404, 11664, 12996, 14400, 15876, 17424, 19044, 20736, 22500, 24336, 26244, 28224, 30276, 32400, 34596, 36864, 39204, 41616, 44100, 46656, 49284, 51984, 54756, 57600, 60516, 63504, 66564, 69696, 72900
Offset: 0

Views

Author

Keywords

Comments

Areas A of two classes of triangles with integer sides (a,b,c) where a = 9k, b=10k and c = 17k, or a = 3k, b = 25k and c = 26k for k=0,1,2,... These areas are given by Heron's formula A = sqrt(s(s-a)(s-b)(s-c)) = (6k)^2, with the semiperimeter s = (a+b+c)/2. This sequence is a subsequence of A188158. - Michel Lagneau, Oct 11 2013
Sequence found by reading the line from 0, in the direction 0, 36, ..., in the square spiral whose vertices are the generalized 20-gonal numbers A218864. - Omar E. Pol, May 13 2018.

Crossrefs

Cf. similar sequences of the type k*n^2: A000290 (k=1), A001105 (k=2), A033428 (k=3), A016742 (k=4), A033429 (k=5), A033581 (k=6), A033582 (k=7), A139098 (k=8), A016766 (k=9), A033583 (k=10), A033584 (k=11), A135453 (k=12), A152742 (k=13), A144555 (k=14), A064761 (k=15), A016802 (k=16), A244630 (k=17), A195321 (k=18), A244631 (k=19), A195322 (k=20), A064762 (k=21), A195323 (k=22), A244632 (k=23), A195824 (k=24), A016850 (k=25), A244633 (k=26), A244634 (k=27), A064763 (k=28), A244635 (k=29), A244636 (k=30).

Programs

Formula

From Ilya Gutkovskiy, Jun 09 2016: (Start)
O.g.f.: 36*x*(1 + x)/(1 - x)^3.
E.g.f.: 36*x*(1 + x)*exp(x).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
Sum_{n>=1} 1/a(n) = Pi^2/216 = A086726. (End)
Product_{n>=1} a(n)/A136017(n) = Pi/3. - Fred Daniel Kline, Jun 09 2016
a(n) = t(9*n) - 9*t(n), where t(i) = i*(i+k)/2 for any k. Special case (k=1): a(n) = A000217(9*n) - 9*A000217(n). - Bruno Berselli, Aug 31 2017
a(n) = 36*A000290(n) = 18*A001105(n) = 12*A033428 = 9*A016742(n) = 6*A033581(n) = 4*A016766(n) = 3*A135453(n) = 2*A195321(n). - Omar E. Pol, Jun 07 2018
Sum_{n>=1} (-1)^(n+1)/a(n) = Pi^2/432. - Amiram Eldar, Jun 27 2020
From Amiram Eldar, Jan 25 2021: (Start)
Product_{n>=1} (1 + 1/a(n)) = sinh(Pi/6)/(Pi/6).
Product_{n>=1} (1 - 1/a(n)) = sin(Pi/6)/(Pi/6) = 3/Pi (A089491). (End)

A244636 a(n) = 30*n^2.

Original entry on oeis.org

0, 30, 120, 270, 480, 750, 1080, 1470, 1920, 2430, 3000, 3630, 4320, 5070, 5880, 6750, 7680, 8670, 9720, 10830, 12000, 13230, 14520, 15870, 17280, 18750, 20280, 21870, 23520, 25230, 27000, 28830, 30720, 32670, 34680, 36750, 38880, 41070, 43320, 45630, 48000, 50430
Offset: 0

Views

Author

Vincenzo Librandi, Jul 03 2014

Keywords

Comments

Sequence found by reading the line from 0, in the direction 0, 30, ..., in the square spiral whose vertices are the generalized 17-gonal numbers. - Omar E. Pol, Jul 03 2014

Crossrefs

Cf. similar sequences listed in A244630.

Programs

  • Magma
    [30*n^2: n in [0..40]];
    
  • Maple
    A244636:=n->30*n^2: seq(A244636(n), n=0..50); # Wesley Ivan Hurt, Jul 04 2014
  • Mathematica
    Table[30 n^2, {n, 0, 40}]
    CoefficientList[Series[30x (1+x)/(1-x)^3,{x,0,50}],x] (* or *) LinearRecurrence[ {3,-3,1},{0,30,120},50] (* Harvey P. Dale, Dec 02 2021 *)
  • PARI
    a(n)=30*n^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: 30*x*(1 + x)/(1 - x)^3. [corrected by Bruno Berselli, Jul 03 2014]
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
a(n) = 30*A000290(n) = 15*A001105(n) = 10*A033428(n) = 6*A033429(n) = 5*A033581(n) = 3*A033583(n) = 2*A064761(n). - Omar E. Pol, Jul 03 2014
From Elmo R. Oliveira, Dec 02 2024: (Start)
E.g.f.: 30*x*(1 + x)*exp(x).
a(n) = n*A249674(n) = A330451(3*n). (End)

A064762 a(n) = 21*n^2.

Original entry on oeis.org

0, 21, 84, 189, 336, 525, 756, 1029, 1344, 1701, 2100, 2541, 3024, 3549, 4116, 4725, 5376, 6069, 6804, 7581, 8400, 9261, 10164, 11109, 12096, 13125, 14196, 15309, 16464, 17661, 18900, 20181, 21504, 22869, 24276, 25725, 27216, 28749
Offset: 0

Views

Author

Roberto E. Martinez II, Oct 18 2001

Keywords

Comments

Number of edges in a complete 7-partite graph of order 7n, K_n,n,n,n,n,n,n.

Crossrefs

Similar sequences are listed in A244630.

Programs

Formula

a(n) = 42*n + a(n-1) - 21 for n > 0, a(0)=0. - Vincenzo Librandi, Aug 07 2010
a(n) = 21*A000290(n) = 7*A033428(n) = 3*A033582(n). - Omar E. Pol, Jul 03 2014
a(n) = t(7*n) - 7*t(n), where t(i) = i*(i+k)/2 for any k. Special case (k=1): a(n) = A000217(7*n) - 7*A000217(n). - Bruno Berselli, Aug 31 2017
From Elmo R. Oliveira, Nov 30 2024: (Start)
G.f.: 21*x*(1 + x)/(1-x)^3.
E.g.f.: 21*x*(1 + x)*exp(x).
a(n) = n*A008603(n) = A195049(2*n).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2. (End)

A244633 a(n) = 26*n^2.

Original entry on oeis.org

0, 26, 104, 234, 416, 650, 936, 1274, 1664, 2106, 2600, 3146, 3744, 4394, 5096, 5850, 6656, 7514, 8424, 9386, 10400, 11466, 12584, 13754, 14976, 16250, 17576, 18954, 20384, 21866, 23400, 24986, 26624, 28314, 30056, 31850, 33696, 35594, 37544, 39546, 41600, 43706
Offset: 0

Views

Author

Vincenzo Librandi, Jul 03 2014

Keywords

Comments

Sequence found by reading the line from 0, in the direction 0, 26, ..., in the square spiral whose vertices are the generalized 15-gonal numbers. - Omar E. Pol, Jul 03 2014
Norms of purely imaginary numbers in Z[sqrt(-26)]. - Alonso del Arte, Dec 25 2014

Crossrefs

Cf. similar sequences listed in A244630.

Programs

Formula

G.f.: 26*x*(1 + x)/(1 - x)^3. [corrected by Bruno Berselli, Jul 03 2014]
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
a(n) = 26*A000290(n) = 13*A001105(n) = 2*A152742(n). - Omar E. Pol, Jul 03 2014
From Elmo R. Oliveira, Dec 02 2024: (Start)
E.g.f.: 26*x*(1 + x)*exp(x).
a(n) = n*A252994(n) = A005843(n)*A008595(n). (End)

A244631 a(n) = 19*n^2.

Original entry on oeis.org

0, 19, 76, 171, 304, 475, 684, 931, 1216, 1539, 1900, 2299, 2736, 3211, 3724, 4275, 4864, 5491, 6156, 6859, 7600, 8379, 9196, 10051, 10944, 11875, 12844, 13851, 14896, 15979, 17100, 18259, 19456, 20691, 21964, 23275, 24624, 26011, 27436, 28899, 30400, 31939, 33516
Offset: 0

Views

Author

Vincenzo Librandi, Jul 03 2014

Keywords

Comments

First bisection of A195048. - Bruno Berselli, Jul 03 2014

Crossrefs

Cf. similar sequences listed in A244630.

Programs

  • Magma
    [19*n^2: n in [0..40]];
    
  • Mathematica
    Table[19 n^2, {n, 0, 40}]
  • PARI
    a(n)=19*n^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: 19*x*(1 + x)/(1 - x)^3. [corrected by Bruno Berselli, Jul 03 2014]
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
a(n) = 19*A000290(n). - Omar E. Pol, Jul 03 2014
From Elmo R. Oliveira, Dec 01 2024: (Start)
E.g.f.: 19*x*(1 + x)*exp(x).
a(n) = n*A008601(n) = A195048(2*n). (End)

A244632 a(n) = 23*n^2.

Original entry on oeis.org

0, 23, 92, 207, 368, 575, 828, 1127, 1472, 1863, 2300, 2783, 3312, 3887, 4508, 5175, 5888, 6647, 7452, 8303, 9200, 10143, 11132, 12167, 13248, 14375, 15548, 16767, 18032, 19343, 20700, 22103, 23552, 25047, 26588, 28175, 29808, 31487, 33212, 34983, 36800, 38663
Offset: 0

Views

Author

Vincenzo Librandi, Jul 03 2014

Keywords

Comments

First bisection of A195058. - Bruno Berselli, Jul 03 2014

Crossrefs

Cf. similar sequences listed in A244630.

Programs

  • Magma
    [23*n^2: n in [0..40]];
    
  • Mathematica
    Table[23 n^2, {n, 0, 40}]
    LinearRecurrence[{3,-3,1},{0,23,92},50] (* Harvey P. Dale, Jul 14 2024 *)
  • PARI
    a(n)=23*n^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: 23*x*(1 + x)/(1 - x)^3. [corrected by Bruno Berselli, Jul 03 2014]
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
a(n) = 23*A000290(n). - Omar E. Pol, Jul 03 2014
From Elmo R. Oliveira, Dec 01 2024: (Start)
E.g.f.: 23*x*(1 + x)*exp(x).
a(n) = n*A008605(n) = A195058(2*n). (End)

A244634 a(n) = 27*n^2.

Original entry on oeis.org

0, 27, 108, 243, 432, 675, 972, 1323, 1728, 2187, 2700, 3267, 3888, 4563, 5292, 6075, 6912, 7803, 8748, 9747, 10800, 11907, 13068, 14283, 15552, 16875, 18252, 19683, 21168, 22707, 24300, 25947, 27648, 29403, 31212, 33075, 34992, 36963, 38988, 41067, 43200, 45387
Offset: 0

Views

Author

Vincenzo Librandi, Jul 03 2014

Keywords

Crossrefs

Cf. similar sequences listed in A244630.

Programs

  • Magma
    [27*n^2: n in [0..40]];
    
  • Mathematica
    Table[27 n^2, {n, 0, 40}]
  • PARI
    a(n)=27*n^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: 27*x*(1 + x)/(1 - x)^3. [corrected by Bruno Berselli, Jul 03 2014]
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
a(n) = 27*A000290(n) = 9*A033428(n) = 3*A016766(n). - Omar E. Pol, Jul 03 2014
From Elmo R. Oliveira, Dec 01 2024: (Start)
E.g.f.: 27*x*(1 + x)*exp(x).
a(n) = n*A305548(n). (End)

A244635 a(n) = 29*n^2.

Original entry on oeis.org

0, 29, 116, 261, 464, 725, 1044, 1421, 1856, 2349, 2900, 3509, 4176, 4901, 5684, 6525, 7424, 8381, 9396, 10469, 11600, 12789, 14036, 15341, 16704, 18125, 19604, 21141, 22736, 24389, 26100, 27869, 29696, 31581, 33524, 35525, 37584, 39701, 41876, 44109, 46400, 48749
Offset: 0

Views

Author

Vincenzo Librandi, Jul 03 2014

Keywords

Crossrefs

Cf. similar sequences listed in A244630.

Programs

  • Magma
    [29*n^2: n in [0..40]];
    
  • Mathematica
    Table[29 n^2, {n, 0, 40}]
  • PARI
    a(n)=29*n^2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

G.f.: 29*x*(1 + x)/(1 - x)^3. [corrected by Bruno Berselli, Jul 03 2014]
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2.
a(n) = 29*A000290(n). - Omar E. Pol, Jul 03 2014
From Elmo R. Oliveira, Dec 01 2024: (Start)
E.g.f.: 29*x*(1 + x)*exp(x).
a(n) = n*A195819(n). (End)
Showing 1-10 of 14 results. Next