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.

A127483 Numbers n such that A100705(n) = n^3 + (n+1)^2 is prime.

Original entry on oeis.org

1, 2, 3, 4, 8, 9, 13, 14, 15, 17, 22, 23, 24, 25, 30, 32, 34, 35, 38, 39, 42, 45, 50, 58, 60, 64, 65, 79, 83, 85, 88, 90, 92, 94, 98, 99, 100, 102, 113, 115, 122, 125, 127, 130, 133, 134, 137, 140, 144, 147, 148, 153, 154, 157, 164, 167, 170, 178, 179, 184, 190, 193
Offset: 1

Views

Author

Alexander Adamchuk, Jan 16 2007

Keywords

Comments

Corresponding primes of the form n^3 + (n+1)^2 are listed in A100662(n) = {5, 17, 43, 89, 593, 829, 2393, 2969, 3631, 5237, ...}.
Note that there are many consecutive twins, triples and quadruplets in a(n). For example: (1,2,3,4), {8,9}, {13,14,15}, {22,23,24,25}, {34,35}, {38,39}, {64,65}, {98,99,100}.
Twins start with n = {1,2,3,8,13,14,22,23,24,34,38,64,98,99,,...} = A127484, or numbers n such that a(n) = a(n+1) - 1.
Triplets start with n = {1,2,13,22,23,98,253,343,573,638,702,...} = A127485, or numbers n such that a(n) = a(n+1) - 1 = a(n+2) - 2.
Quadruplets start with n = {1,22,13077,14267,16092,16267,162,...} = A127486.

Crossrefs

Programs

  • Mathematica
    Select[Range[1000],PrimeQ[ #^3+(#+1)^2]&]

A268261 T(n,k)=Number of length-(n+1) 0..k arrays with new repeated values introduced in sequential order starting with zero.

Original entry on oeis.org

3, 7, 5, 13, 17, 9, 21, 43, 42, 17, 31, 89, 143, 106, 33, 43, 161, 378, 479, 273, 65, 57, 265, 837, 1610, 1616, 717, 129, 73, 407, 1634, 4357, 6877, 5492, 1918, 257, 91, 593, 2907, 10082, 22710, 29461, 18804, 5218, 513, 111, 829, 4818, 20771, 62249, 118530, 126591
Offset: 1

Views

Author

R. H. Hardin, Jan 29 2016

Keywords

Comments

Table starts
....3.....7.....13.......21.......31........43.........57..........73
....5....17.....43.......89......161.......265........407.........593
....9....42....143......378......837......1634.......2907........4818
...17...106....479.....1610.....4357.....10082......20771.......39154
...33...273...1616.....6877....22710.....62249.....148468......318261
...65...717...5492....29461...118530....384605....1061632.....2587557
..129..1918..18804...126591...619490...2377935....7594224....21042479
..257..5218..64869...545627..3242265..14712729...54345509...171161319
..513.14413.225483..2359152.16993552..91096234..389060724..1392571084
.1025.40349.789747.10233188.89197862.564452368.2786424182.11332701236

Examples

			Some solutions for n=5 k=4
..0....4....1....2....0....3....2....1....0....1....4....1....1....1....3....2
..0....3....4....4....0....2....4....0....3....4....0....3....0....2....4....0
..4....4....0....0....4....3....3....0....2....1....4....4....4....3....0....0
..3....0....2....0....0....4....4....4....0....4....1....0....3....2....3....4
..1....0....3....1....2....0....1....3....3....0....0....3....1....3....0....3
..3....3....2....4....0....0....4....0....2....3....3....1....3....0....4....0
		

Crossrefs

Column 1 is A000051.
Row 1 is A002061(n+1).
Row 2 is A100705.

Formula

Empirical for column k:
k=1: a(n) = 3*a(n-1) -2*a(n-2)
k=2: a(n) = 7*a(n-1) -15*a(n-2) +7*a(n-3) +6*a(n-4)
k=3: a(n) = 13*a(n-1) -60*a(n-2) +105*a(n-3) -11*a(n-4) -94*a(n-5) -24*a(n-6)
k=4: [order 8]
k=5: [order 10]
k=6: [order 12]
k=7: [order 14]
Empirical for row n:
n=1: a(n) = n^2 + n + 1
n=2: a(n) = n^3 + n^2 + 2*n + 1
n=3: a(n) = n^4 + n^3 + 3*n^2 + 2*n + 2
n=4: a(n) = n^5 + n^4 + 4*n^3 + 3*n^2 + 6*n + 2
n=5: a(n) = n^6 + n^5 + 5*n^4 + 4*n^3 + 12*n^2 + 6*n + 5 for n>1
n=6: a(n) = n^7 + n^6 + 6*n^5 + 5*n^4 + 20*n^3 + 12*n^2 + 20*n + 5 for n>1
n=7: a(n) = n^8 + n^7 + 7*n^6 + 6*n^5 + 30*n^4 + 20*n^3 + 50*n^2 + 20*n + 15 for n>2

A255741 Square array read by antidiagonals upwards: T(n,k), n>=1, k>=1, in which row n lists the partial sums of the n-th row of the square array of A255740.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 5, 3, 1, 1, 5, 7, 7, 4, 1, 1, 6, 9, 13, 9, 4, 1, 1, 7, 11, 21, 16, 11, 4, 1, 1, 8, 13, 31, 25, 22, 13, 4, 1, 1, 9, 15, 43, 36, 37, 28, 15, 5, 1, 1, 10, 17, 57, 49, 56, 49, 40, 17, 5, 1, 1, 11, 19, 73, 64, 79, 76, 85, 43, 19, 5, 1, 1, 12, 21, 91, 81, 106, 109, 156, 89, 49, 21, 5, 1
Offset: 1

Views

Author

Omar E. Pol, Mar 05 2015

Keywords

Examples

			The corner of the square array with the first 15 terms of the first 12 rows looks like this:
-------------------------------------------------------------------------
A000012: 1, 1, 1,  1,  1,  1,  1,   1,   1,   1,   1,   1,   1,   1,   1
A070941: 1, 2, 3,  3,  4,  4,  4,   4,   5,   5,   5,   5,   5,   5,   5
A005408: 1, 3, 5,  7,  9, 11, 13,  15,  17,  19,  21,  23,  25,  27,  29
A151788: 1, 4, 7, 13, 16, 22, 28,  40,  43,  49,  55,  67,  73,  85,  97
A147562: 1, 5, 9, 21, 25, 37, 49,  85,  89, 101, 113, 149, 161, 197, 233
A151790: 1, 6,11, 31, 36, 56, 76, 156, 161, 181, 201, 281, 301, 381, 461
A151781: 1, 7,13, 43, 49, 79,109, 259, 265, 295, 325, 475, 505, 655, 805
A151792: 1, 8,15, 57, 64,106,148, 400, 407, 449, 491, 743, 785,1037,1289
A151793: 1, 9,17, 73, 81,137,193, 585, 593, 649, 705,1097,1153,1545,1937
A255764: 1,10,19, 91,100,172,244, 820, 829, 901, 973,1549,1621,2197,2773
A255765: 1,11,21,111,121,211,301,1111,1121,1211,1301,2111,2201,3011,3821
A255766: 1,12,23,133,144,254,364,1464,1475,1585,1695,2795,2905,4005,5105
...
		

Crossrefs

A100662 Primes of the form k^3 + (k+1)^2.

Original entry on oeis.org

5, 17, 43, 89, 593, 829, 2393, 2969, 3631, 5237, 11177, 12743, 14449, 16301, 27961, 33857, 40529, 44171, 56393, 60919, 75937, 93241, 127601, 198593, 219721, 266369, 278981, 499439, 578843, 621521, 689393, 737281, 787337, 839609, 950993, 980299, 1010201, 1071817
Offset: 1

Views

Author

Giovanni Teofilatto, Jan 03 2005

Keywords

Examples

			a(1) = 5 because 5 = 1^3 + 2^2.
a(2) = 17 because 17 = 2^3 + 3^2.
a(3) = 43 because 43 = 3^3 + 4^2.
		

Crossrefs

Intersection of A100705 and A000040.
Cf. A127483.

Programs

  • Magma
    [ a: n in [0..100] | IsPrime(a) where a is n^3 + (n+1)^2 ]; // Vincenzo Librandi, Jul 18 2012
    
  • Mathematica
    Select[Table[n^3+(n+1)^2,{n,200}],PrimeQ] (* Vladimir Joseph Stephan Orlovsky, Feb 01 2012 *)
  • PARI
    list(lim)=my(v=List(),t); for(n=1,lim, t=n^3+(n+1)^2; if(t>lim, break); if(isprime(t), listput(v,t))); Vec(v) \\ Charles R Greathouse IV, Dec 23 2016

Formula

a(n) = A100705(A127483(n)). - Elmo R. Oliveira, Apr 19 2025

Extensions

More terms from Mark Hudson, Jan 04 2005

A127484 Numbers k such that A127483(k) = A127483(k+1) - 1.

Original entry on oeis.org

1, 2, 3, 8, 13, 14, 22, 23, 24, 34, 38, 64, 98, 99, 133, 147, 153, 178, 232, 253, 254, 297, 328, 343, 344, 367, 407, 498, 573, 574, 582, 587, 624, 638, 639, 653, 668, 679, 702, 703, 759, 772, 793, 797, 849, 874, 944, 958, 1023, 1058, 1067, 1087, 1203, 1212, 1322
Offset: 1

Views

Author

Alexander Adamchuk, Jan 16 2007

Keywords

Comments

A127483(n) = {1,2,3,4,8,9,13,14,15,17,22,23,24,25,30,32,34,35,38,39,42,45,50,...} are the numbers n such that A100705(n) = n^3 + (n+1)^2 is prime.
Corresponding primes of the form n^3 + (n+1)^2 are listed in A100662(n) = {5, 17, 43, 89, 593, 829, 2393, 2969, 3631, 5237, ...}.
Note that there are many consecutive twins, triples and quadruplets in A127483(n). For example: (1,2,3,4), {8,9}, {13,14,15}, {22,23,24,25}, {34,35}, {38,39}, {64,65}, {98,99,100}. Twins in A127483(k) start with numbers k = a(n). Triplets in A127483(k) start with k = {1,2,13,22,23,98,253,343,573,638,702,...} = A127485, or numbers n such that a(k) = a(k+1) - 1 = a(k+2) - 2. Quadruplets in A127483(k) start with k = {1,22,13077,14267,16092,16267,16282,36387,47012,51912,54662,...} = A127486.

Crossrefs

Programs

  • Magma
    [k:k in [1..1350]|IsPrime(k^3+(k+1)^2) and IsPrime((k+1)^3+(k+2)^2)]; // Marius A. Burtea, Jan 20 2020
  • Mathematica
    Select[Range[3000],PrimeQ[ #^3+(#+1)^2]&&PrimeQ[(#+1)^3+(#+2)^2]&]

A127485 Numbers k such that A127483(k) = A127483(k+1) - 1 = A127483(k+2) - 2.

Original entry on oeis.org

1, 2, 13, 22, 23, 98, 253, 343, 573, 638, 702, 1322, 1862, 2543, 2638, 2758, 2792, 2912, 3093, 3158, 3242, 3578, 3968, 4382, 5013, 6503, 7048, 7877, 8372, 8912, 9022, 9207, 10298, 10443, 11538, 12482, 13077, 13078, 13868, 14267, 14268, 14323, 14783
Offset: 1

Views

Author

Alexander Adamchuk, Jan 16 2007

Keywords

Comments

A127483(n) = {1,2,3,4,8,9,13,14,15,17,22,23,24,25,30,32,34,35,38,39,42,45,50,...} are the numbers n such that A100705(n) = n^3 + (n+1)^2 is prime. Corresponding primes of the form n^3 + (n+1)^2 are listed in A100662(n) = {5, 17, 43, 89, 593, 829, 2393, 2969, 3631, 5237, ...}. Note that there are many consecutive twins, triples and quadruplets in A127483(n). For example: (1,2,3,4), {8,9}, {13,14,15}, {22,23,24,25}, {34,35}, {38,39}, {64,65}, {98,99,100}. Twins in A127483(k) start with k = {1,2,3,8,13,14,22,23,24,34,38,64,98,99,133,147,153,178,232,253,254,297,328,343, 344,367,407,498,...} = A127484. Triplets in A127483(k) start with numbers k = a(n). Quadruplets in A127483(k) start with k = {1,22,13077,14267,16092,16267,16282,36387,47012,51912,54662,...} = A127486.

Crossrefs

Programs

  • Magma
    f:=func; [k:k in [1..15000]|f(k) and f(k+1) and f(k+2)]; // Marius A. Burtea, Jan 20 2020
  • Mathematica
    Select[Range[30000],PrimeQ[ #^3+(#+1)^2]&&PrimeQ[(#+1)^3+(#+2)^2]&&PrimeQ[(#+2)^3+(#+3)^2]&]

A127486 Numbers k such that A127483(k) = A127483(k+1) - 1 = A127483(k+2) - 2 = A127483(k+3) - 3.

Original entry on oeis.org

1, 22, 13077, 14267, 16092, 16267, 16282, 36387, 47012, 51912, 54662, 144487, 181777, 205897, 210022, 213982, 250517, 263717, 344092, 409697, 454607, 568777, 643677, 665917, 702947, 749967, 824167, 858187, 887677, 888427, 997787, 1075537
Offset: 1

Views

Author

Alexander Adamchuk, Jan 16 2007

Keywords

Comments

A127483(n) = {1,2,3,4,8,9,13,14,15,17,22,23,24,25,30,32,34,35,38,39,42,45,50,...} are the numbers n such that A100705(n) = n^3 + (n+1)^2 is prime. Corresponding primes of the form n^3 + (n+1)^2 are listed in A100662(n) = {5, 17, 43, 89, 593, 829, 2393, 2969, 3631, 5237, ...}. Note that there are many consecutive twins, triples and quadruplets in A127483(n). For example: (1,2,3,4), {8,9}, {13,14,15}, {22,23,24,25}, {34,35}, {38,39}, {64,65}, {98,99,100}. Twins in A127483(k) start with k = {1,2,3,8,13,14,22,23,24,34,38,64,98,99,133,147,153,178,232,253,254,297,328,343, 344,367,407,498,...} = A127484. Triplets in A127483(k) start with k = {1,2,13,22,23,98,253,343,573,638,702,...} = A127485. Quadruplets in A127483(k) start with numbers k = a(n).
For n>1 the final digit of all listed terms of a(n) is 2 or 7. - Alexander Adamchuk, Jan 16 2007

Crossrefs

Programs

  • Mathematica
    f[s_]:=s^3+(s+1)^2; Do[If[PrimeQ[f[n]]&&PrimeQ[f[n+1]]&&PrimeQ[f[n+2]]&&PrimeQ[f[n+3]],Print[n]],{n,1,100000}]

Extensions

More terms from Alexander Adamchuk, Jan 16 2007

A304159 a(n) = 2*n^3 - 4*n^2 + 6*n - 2 (n>=1).

Original entry on oeis.org

2, 10, 34, 86, 178, 322, 530, 814, 1186, 1658, 2242, 2950, 3794, 4786, 5938, 7262, 8770, 10474, 12386, 14518, 16882, 19490, 22354, 25486, 28898, 32602, 36610, 40934, 45586, 50578, 55922, 61630, 67714, 74186, 81058, 88342, 96050, 104194, 112786, 121838, 131362, 141370, 151874, 162886, 174418, 186482, 199090
Offset: 1

Views

Author

Emeric Deutsch, May 09 2018

Keywords

Comments

a(n) is the first Zagreb index of the Barbell graph B(n) (n>=3).
The Barbell graph B(n) is defined as two copies of the complete graph K(n) (n>=3), connected by a bridge.
The first Zagreb index of a simple connected graph is the sum of the squared degrees of its vertices. Alternatively, it is the sum of the degree sums d(i) + d(j) over all edges ij of the graph.
The M-polynomial of the Barbell graph B(n) is M(B(n),x,y) = (n-1)*(n-2)*x^{n-1}*y^{n-1} + 2*(n-1)*x^{n-1}*y^n + x^n*y^n.

Crossrefs

Programs

  • Maple
    seq(2*n^3-4*n^2+6*n-2, n = 1 .. 40);
  • Mathematica
    Table[2n^3-4n^2+6n-2 ,{n,50}] (* or *) LinearRecurrence[{4,-6,4,-1},{2,10,34,86},50] (* Harvey P. Dale, Mar 05 2023 *)
  • PARI
    Vec(2*x*(1 + x + 3*x^2 + x^3) / (1 - x)^4 + O(x^60)) \\ Colin Barker, May 09 2018
    
  • PARI
    a(n) = 2*n^3-4*n^2+6*n-2; \\ Altug Alkan, May 09 2018

Formula

a(n) = 2 * A100705(n-1).
From Colin Barker, May 09 2018: (Start)
G.f.: 2*x*(1 + x + 3*x^2 + x^3) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>4. (End)
a(n) = A033431(n) - A002943(n-1) = A033431(n) - 2*A014105(n-1). - Omar E. Pol, May 09 2018
Showing 1-8 of 8 results.