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 10 results.

A157276 A157107=220,440,661,881,1105, - 220,440,660,880,1100,=220*(n+1)=10*A008604(n+1).

Original entry on oeis.org

0, 0, 1, 1, 5, 5, 6, 6, 11, 11, 12, 12, 16, 16, 17, 17, 31, 31, 32, 32, 36, 36, 37, 37, 42, 42, 43, 43, 47, 47, 48, 48, 66, 66, 67, 67, 71, 71, 72, 72, 77, 77, 78, 78, 82, 82, 83, 83, 97, 97, 98, 98, 102, 102, 103, 103, 108, 108, 109, 109, 113, 113, 114, 114
Offset: 0

Views

Author

Paul Curtz, Feb 26 2009

Keywords

Comments

(From A090822). A157107(0)=220,..,A157107(63)=14194, A157107(64)=14236 ,see 42 in submitted A157206. a(63)=14194-(64*220=14080)=114, a(64)=14236-14300=-64. "Linked" to submitted A156912=1,2,1,5,1,2,1,6,.

A008593 Multiples of 11.

Original entry on oeis.org

0, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 132, 143, 154, 165, 176, 187, 198, 209, 220, 231, 242, 253, 264, 275, 286, 297, 308, 319, 330, 341, 352, 363, 374, 385, 396, 407, 418, 429, 440, 451, 462, 473, 484, 495, 506, 517, 528, 539, 550, 561, 572, 583
Offset: 0

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Author

Keywords

Comments

Numbers for which the sum of "digits" in base 100 is divisible by 11. For instance, 193517302 gives 1 + 93 + 51 + 73 + 02 = 220, and 2 + 20 = 22 = 2 * 11. - Daniel Forgues, Feb 22 2016
Numbers in which the sum of the digits in the even positions equals the sum of the digits in the odd positions. - Stefano Spezia, Jan 05 2025

Crossrefs

Programs

Formula

a(n) = 11*n.
G.f.: 11*x/(1-x)^2. - David Wilding, Jun 21 2014
E.g.f.: 11*x*exp(x). - Stefano Spezia, Oct 08 2022
From Elmo R. Oliveira, Apr 10 2025: (Start)
a(n) = 2*a(n-1) - a(n-2).
a(n) = A008604(n)/2. (End)

A008606 Multiples of 24.

Original entry on oeis.org

0, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, 264, 288, 312, 336, 360, 384, 408, 432, 456, 480, 504, 528, 552, 576, 600, 624, 648, 672, 696, 720, 744, 768, 792, 816, 840, 864, 888, 912, 936, 960, 984, 1008, 1032, 1056, 1080, 1104, 1128, 1152, 1176, 1200
Offset: 0

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Author

Keywords

Comments

If n is a multiple of 24, also the sum of the divisors of n-1 is a multiple of 24. - Vincenzo Librandi, Apr 12 2014
This is the sequence of numbers n such that A259748(n)/n = 11/12. - Danny Rorabaugh, Oct 22 2015

Crossrefs

Programs

Formula

G.f.: 24*x/(1-x)^2. - Vincenzo Librandi, Jun 11 2013
a(n) = 24*A001477(n) - Danny Rorabaugh, Oct 24 2015
E.g.f.: 24*x*exp(x). - Stefano Spezia, Mar 02 2025

A161709 a(n) = 22*n + 1.

Original entry on oeis.org

1, 23, 45, 67, 89, 111, 133, 155, 177, 199, 221, 243, 265, 287, 309, 331, 353, 375, 397, 419, 441, 463, 485, 507, 529, 551, 573, 595, 617, 639, 661, 683, 705, 727, 749, 771, 793, 815, 837, 859, 881, 903, 925, 947, 969, 991, 1013, 1035, 1057, 1079, 1101, 1123
Offset: 0

Views

Author

Reinhard Zumkeller, Jun 17 2009

Keywords

References

  • Italo Ghersi, Matematica dilettevole e curiosa, p. 139, Hoepli, Milano, 1967. [From Vincenzo Librandi, Dec 02 2009]

Crossrefs

Programs

Formula

From G. C. Greubel, Sep 18 2019: (Start)
a(n) = 2*a(n-1) - a(n-2).
G.f.: (1 + 21*x)/(1-x)^2.
E.g.f.: (1 + 22*x)*exp(x). (End)

A195323 a(n) = 22*n^2.

Original entry on oeis.org

0, 22, 88, 198, 352, 550, 792, 1078, 1408, 1782, 2200, 2662, 3168, 3718, 4312, 4950, 5632, 6358, 7128, 7942, 8800, 9702, 10648, 11638, 12672, 13750, 14872, 16038, 17248, 18502, 19800, 21142, 22528, 23958, 25432, 26950, 28512, 30118, 31768, 33462, 35200, 36982, 38808
Offset: 0

Views

Author

Omar E. Pol, Sep 16 2011

Keywords

Comments

Sequence found by reading the line from 0, in the direction 0, 22, ..., in the square spiral whose vertices are the generalized tridecagonal numbers A195313. Semi-axis opposite to A195318 in the same spiral.
Surface area of a rectangular prism with dimensions n, 2n and 3n. - Wesley Ivan Hurt, Apr 10 2015

Crossrefs

Programs

Formula

a(n) = 22*A000290(n) = 11*A001105(n) = 2*A033584(n).
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Harvey P. Dale, Sep 19 2011
G.f.: 22*x*(1+x)/(1-x)^3. - Wesley Ivan Hurt, Apr 10 2015
From Elmo R. Oliveira, Dec 01 2024: (Start)
E.g.f.: 22*x*(1 + x)*exp(x).
a(n) = n*A008604(n) = A195149(2*n). (End)

A008605 Multiples of 23.

Original entry on oeis.org

0, 23, 46, 69, 92, 115, 138, 161, 184, 207, 230, 253, 276, 299, 322, 345, 368, 391, 414, 437, 460, 483, 506, 529, 552, 575, 598, 621, 644, 667, 690, 713, 736, 759, 782, 805, 828, 851, 874, 897, 920, 943, 966, 989, 1012, 1035, 1058, 1081, 1104, 1127, 1150
Offset: 0

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Author

Keywords

Crossrefs

Programs

Formula

G.f.: 23*x/(x-1)^2. - Vincenzo Librandi, Jun 10 2013
E.g.f.: 23*x*exp(x). - Stefano Spezia, Mar 02 2025
From Elmo R. Oliveira, Apr 10 2025: (Start)
a(n) = 23*n = (A008604(n) + A008606(n))/2.
a(n) = 2*a(n-1) - a(n-2). (End)

A317322 Multiples of 22 and odd numbers interleaved.

Original entry on oeis.org

0, 1, 22, 3, 44, 5, 66, 7, 88, 9, 110, 11, 132, 13, 154, 15, 176, 17, 198, 19, 220, 21, 242, 23, 264, 25, 286, 27, 308, 29, 330, 31, 352, 33, 374, 35, 396, 37, 418, 39, 440, 41, 462, 43, 484, 45, 506, 47, 528, 49, 550, 51, 572, 53, 594, 55, 616, 57, 638, 59, 660, 61, 682, 63, 704, 65, 726, 67, 748, 69
Offset: 0

Views

Author

Omar E. Pol, Jul 25 2018

Keywords

Comments

Partial sums give the generalized 26-gonal numbers (A316724).
a(n) is also the length of the n-th line segment of the rectangular spiral whose vertices are the generalized 26-gonal numbers.

Crossrefs

Cf. A008604 and A005408 interleaved.
Column 22 of A195151.
Sequences whose partial sums give the generalized k-gonal numbers: A026741 (k=5), A001477 (k=6), zero together with A080512 (k=7), A022998 (k=8), A195140 (k=9), zero together with A165998 (k=10), A195159 (k=11), A195161 (k=12), A195312 (k=13), A195817 (k=14).
Cf. A316724.

Programs

  • Mathematica
    Module[{nn=40},Riffle[22Range[0,nn],Range[1,2nn,2]]] (* or *) LinearRecurrence[ {0,2,0,-1},{0,1,22,3},80] (* Harvey P. Dale, Dec 12 2021 *)
  • PARI
    concat(0, Vec(x*(1 + 22*x + x^2) / ((1 - x)^2*(1 + x)^2) + O(x^60))) \\ Colin Barker, Jul 29 2018

Formula

a(2n) = 22*n, a(2n+1) = 2*n + 1.
From Colin Barker, Jul 29 2018: (Start)
G.f.: x*(1 + 22*x + x^2) / ((1 - x)^2*(1 + x)^2).
a(n) = 2*a(n-2) - a(n-4) for n>3. (End)
Multiplicative with a(2^e) = 11*2^e, and a(p^e) = p^e for an odd prime p. - Amiram Eldar, Oct 14 2023
Dirichlet g.f.: zeta(s-1) * (1 + 5*2^(2-s)). - Amiram Eldar, Oct 26 2023

A141694 a(n) = 22*n + 12.

Original entry on oeis.org

12, 34, 56, 78, 100, 122, 144, 166, 188, 210, 232, 254, 276, 298, 320, 342, 364, 386, 408, 430, 452, 474, 496, 518, 540, 562, 584, 606, 628, 650, 672, 694, 716, 738, 760, 782, 804, 826, 848, 870, 892, 914, 936, 958, 980, 1002, 1024, 1046, 1068, 1090, 1112
Offset: 0

Views

Author

Paul Curtz, Sep 10 2008

Keywords

Crossrefs

Cf. A008604, A010861 (first differences), A017461.

Programs

Formula

From G. C. Greubel, Jun 03 2018: (Start)
a(n) = 2*a(n-1) - a(n-2).
G.f.: 2*(6 + 5*x)/(1 - x)^2.
E.g.f.: 2*(6 + 11*x)*exp(x). (End)
a(n) = 2*A017461(n). - Elmo R. Oliveira, Apr 11 2025

Extensions

Edited by R. J. Mathar, Oct 24 2008
Offset changed from 1 to 0 by Vincenzo Librandi, Aug 08 2011

A247128 Positive numbers that are congruent to {0,5,9,13,17} mod 22.

Original entry on oeis.org

5, 9, 13, 17, 22, 27, 31, 35, 39, 44, 49, 53, 57, 61, 66, 71, 75, 79, 83, 88, 93, 97, 101, 105, 110, 115, 119, 123, 127, 132, 137, 141, 145, 149, 154, 159, 163, 167, 171, 176, 181, 185, 189, 193, 198, 203, 207, 211
Offset: 1

Views

Author

Karl V. Keller, Jr., Nov 19 2014

Keywords

Comments

This sequence is the union of 22*n-17, 22*n-13, 22*n-9, and 22*n-5, and A008604(22*n), for n>0.
This sequence is the integer values of sqrt(4*k - ceiling(k/3) + 3 + k mod 2), for k>0; see example.
The sequence numbers with both odd first and last digits are either palindromes or they have corresponding reversed digit numbers, e.g., 105, 501. Prime numbers in this sequence are also in A007500 (reversal primes). Some examples are 13, 17, 31, 71, 79, 97, 101.
The sequence numbers with even first digits and last digits of 2, 4, 6 or 8, are either palindromes or they have corresponding reversed digit numbers in this sequence.
The candidate Lychrel numbers, 295, 493, 691, 1677, 1765, 1857, 1945, 1997, 3493, are in this sequence.

Examples

			Sequence consists of the integer values of sqrt(4*k - ceiling(k/3) + 3 + k mod 2), for k>0; e.g.,
for k =  5, sqrt( 20 -  2 + 3 + 1) = sqrt(22)  =  4.6904;
for k =  6, sqrt( 24 -  2 + 3 + 0) = sqrt(25)  =  5;
for k = 21, sqrt( 84 -  7 + 3 + 1) = sqrt(81)  =  9;
for k = 44, sqrt(176 - 15 + 3 + 0) = sqrt(164) = 12.8062;
for k = 45, sqrt(180 - 15 + 3 + 1) = sqrt(169) = 13.
Of these, the only integer values are 5, 9, 13, so they are in the sequence.
		

Crossrefs

Cf. A008604, A002113 (palindromes), A007500 (reversible primes).
Cf. A023108.

Programs

  • Mathematica
    a247128[n_Integer] := Select[Range[n], MemberQ[{0, 5, 9, 13, 17}, Mod[#, 22]] &]; a247128[211] (* Michael De Vlieger, Nov 23 2014 *)
  • PARI
    isok(n) = m = n % 22; (m==0) || (m==5) || (m==9) || (m==13) || (m==17);
    select(x->isok(x), vector(200, i, i)) \\ Michel Marcus, Nov 28 2014
    
  • Python
    from math import *
    for n in range(0,100001):
      if (sqrt(4*n-ceil(n/3)+3+n%2))%1==0:print(int(sqrt(4*n-ceil(n/3)+3+n%2)),end=",")
    
  • Python
    A247128_list = [n for n in range(1,10**5) if (n % 22) in {0,5,9,13,17}]
    # Chai Wah Wu, Dec 31 2014
    
  • Python
    A247128_list, l = [], [5,9,13,17,22]
    for _ in range(10**5):
        A247128_list.extend(l)
        l = [x+22 for x in l] # Chai Wah Wu, Jan 01 2015

Formula

a(n) = a(n-1) + a(n-5) - a(n-6). - Colin Barker, Nov 20 2014
G.f.: x*(5*x^4+4*x^3+4*x^2+4*x+5) / ((x-1)^2*(x^4+x^3+x^2+x+1)). - Colin Barker, Nov 20 2014
Proof that a(n) = a(n-1) + a(n-5) - a(n-6): the sequence a(n) is a concatenation of the sequences [5+22*i, 9+22*i, 13+22*i, 17+22*i, 22+22*i] for i = 0,1,2,..., so it is clear that a(n-1) = a(n-6) + 22 and a(n) = a(n-5) + 22. - Chai Wah Wu, Jan 01 2015

A233207 Triangle T(n,k), read by rows, given by T(n+k,k)=2*k*(2*n+1).

Original entry on oeis.org

0, 0, 2, 0, 6, 4, 0, 10, 12, 6, 0, 14, 20, 18, 8, 0, 18, 28, 30, 24, 10, 0, 22, 36, 42, 40, 30, 12, 0, 26, 44, 54, 56, 50, 36, 14, 0, 30, 52, 66, 72, 70, 60, 42, 16, 0, 34, 60, 78, 88, 90, 84, 70, 48, 18, 0, 38, 68, 90, 104, 110, 108, 98, 80, 54, 20, 0, 42, 76, 102
Offset: 0

Views

Author

Philippe Deléham, Dec 05 2013

Keywords

Comments

Row sums are A006331(n).
Diagonal sums are A212964(n+1).
T(2n,n)=A002943(n).

Examples

			Triangle begins:
  0
  0, 2
  0, 6, 4
  0, 10, 12, 6
  0, 14, 20, 18, 8
  0, 18, 28, 30, 24, 10
		

Crossrefs

Formula

T(n+k,k) = A005843(k)*A005408(n).
Sum_{k=0..n} T(n,k) = n*(n+1)*(2*n+1)/3 = A006331(n).
Showing 1-10 of 10 results.