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 1-7 of 7 results.

A017281 a(n) = 10*n + 1.

Original entry on oeis.org

1, 11, 21, 31, 41, 51, 61, 71, 81, 91, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 201, 211, 221, 231, 241, 251, 261, 271, 281, 291, 301, 311, 321, 331, 341, 351, 361, 371, 381, 391, 401, 411, 421, 431, 441, 451, 461, 471, 481, 491, 501, 511, 521, 531
Offset: 0

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Comments

Equals [1, 2, 3, ...] convolved with [1, 9, 0, 0, 0, ...]. - Gary W. Adamson, May 30 2009
Let A be the Hessenberg matrix of order n, defined by: A[1,j]=1, A[i,i]:=10, (i>1), A[i,i-1] = -1, and A[i,j]=0 otherwise. Then, for n>=2, a(n-1) = -coeff(charpoly(A,x),x^(n-1)). - Milan Janjic, Feb 21 2010
Positive integers with last decimal digit = 1. - Wesley Ivan Hurt, Jun 17 2015
Also the number of (not necessarily maximal) cliques in the 2n-crossed prism graph. - Eric W. Weisstein, Nov 29 2017
From Martin Renner, May 28 2024: (Start)
Also number of squares in a grid cross with equally long arms and a width of two points (cf. A017113), e.g. for n = 2 there are nine squares of size 1 unit of area, four of size 2, two of size 5, four of size 8 and two of size 13, thus a total of 21 squares.
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The possible areas of the squares are given by ceiling(k^2/2) for 1 <= k <= 2*n+1, cf. A000982. In general, there are 4*n + 1 squares with one unit area to be found in the cross, cf. A016813, for n > 0 always four squares of even area and two squares of odd area > 1. (End)

Crossrefs

Cf. A093645 (column 1).
Subsequence of A034709, together with A017293, A017329, A139222, A139245, A139249, A139264, A139279 and A139280.
Cf. A030430 (primes).
Cf. A272914, first comment. [Bruno Berselli, May 26 2016]

Programs

Formula

G.f.: (1+9*x)/(1-x)^2.
a(n) = 20*n - a(n-1) - 8, with a(0)=1. - Vincenzo Librandi, Nov 20 2010
a(n) = 2*a(n-1) - a(n-2), for n > 2. - Wesley Ivan Hurt, Jun 17 2015
E.g.f.: (1 + 10*x)*exp(x). - G. C. Greubel, Sep 18 2019

A017311 a(n) = (10*n + 3)^7.

Original entry on oeis.org

2187, 62748517, 3404825447, 42618442977, 271818611107, 1174711139837, 3938980639167, 11047398519097, 27136050989627, 60170087060757, 122987386542487, 235260548044817, 425927596977747, 736141813551277
Offset: 0

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Cf. A272914, first comment. - Bruno Berselli, May 26 2016

Programs

  • Magma
    [(10*n+3)^7: n in [0..20]]; // Vincenzo Librandi, Jul 31 2011
  • Mathematica
    (10Range[0,20]+3)^7 (* or *) LinearRecurrence[{8,-28,56,-70,56,-28,8,-1},{2187,62748517,3404825447,42618442977,271818611107,1174711139837,3938980639167,11047398519097},20] (* Harvey P. Dale, Oct 02 2017 *)

A017322 a(n) = (10*n + 4)^6.

Original entry on oeis.org

4096, 7529536, 191102976, 1544804416, 7256313856, 24794911296, 68719476736, 164206490176, 351298031616, 689869781056, 1265319018496, 2194972623936, 3635215077376, 5789336458816, 8916100448256
Offset: 0

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First bisection of A272914.

Programs

A017333 a(n) = (10*n + 5)^5.

Original entry on oeis.org

3125, 759375, 9765625, 52521875, 184528125, 503284375, 1160290625, 2373046875, 4437053125, 7737809375, 12762815625, 20113571875, 30517578125, 44840334375, 64097340625, 89466096875, 122298103125, 164130859375, 216699865625, 281950621875, 362050628125, 459401384375
Offset: 0

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Crossrefs

Cf. A272914 (first comment). [Bruno Berselli, May 26 2016]

Programs

  • Magma
    [(10*n+5)^5: n in [0..25]]; // Vincenzo Librandi, Aug 02 2011
  • Mathematica
    (10*Range[0,20]+5)^5 (* or *) LinearRecurrence[{6,-15,20,-15,6,-1},{3125,759375,9765625,52521875,184528125,503284375},20] (* Harvey P. Dale, May 15 2018 *)

Formula

G.f.: 3125*(x+1)*(x^4+236*x^3+1446*x^2+236*x+1)/(x-1)^6. - Colin Barker, Nov 14 2012
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^5.
a(n) = 5^5 * A016757(n).
Sum_{n>=0} 1/a(n) = 31*zeta(5)/100000.
Sum_{n>=0} (-1)^n/a(n) = Pi^5/960000. (End)

A017346 a(n) = (10*n + 6)^6.

Original entry on oeis.org

46656, 16777216, 308915776, 2176782336, 9474296896, 30840979456, 82653950016, 192699928576, 404567235136, 782757789696, 1418519112256, 2436396322816, 4001504141376, 6327518887936, 9685390482496
Offset: 0

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Second bisection of A272914.

Programs

A017355 a(n) = (10*n + 7)^3.

Original entry on oeis.org

343, 4913, 19683, 50653, 103823, 185193, 300763, 456533, 658503, 912673, 1225043, 1601613, 2048383, 2571353, 3176523, 3869893, 4657463, 5545233, 6539203, 7645373, 8869743, 10218313, 11697083
Offset: 0

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Crossrefs

Cf. A272914, first comment. [From Bruno Berselli, May 26 2016]

Programs

  • Magma
    [(10*n+7)^3: n in [0..40]]; // Vincenzo Librandi, Aug 30 2011
  • Mathematica
    (10 Range[0, 40] + 7)^3 (* or *) LinearRecurrence[{4, -6, 4, -1}, {343, 4913, 19683, 50653}, 40] (* Harvey P. Dale, Jun 11 2015 *)

Formula

a(0)=343, a(1)=4913, a(2)=19683, a(3)=50653; for n>3, a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). - Harvey P. Dale, Jun 11 2015

A017385 a(n) = (10*n + 9)^9.

Original entry on oeis.org

387420489, 322687697779, 14507145975869, 208728361158759, 1628413597910449, 8662995818654939, 35452087835576229, 119851595982618319, 350356403707485209, 913517247483640899, 2171893279442309389
Offset: 0

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Crossrefs

Cf. A272914, first comment. [From Bruno Berselli, May 26 2016]

Programs

Showing 1-7 of 7 results.