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 1-3 of 3 results.

A100188 Polar structured meta-anti-diamond numbers, the n-th number from a polar structured n-gonal anti-diamond number sequence.

Original entry on oeis.org

1, 6, 27, 84, 205, 426, 791, 1352, 2169, 3310, 4851, 6876, 9477, 12754, 16815, 21776, 27761, 34902, 43339, 53220, 64701, 77946, 93127, 110424, 130025, 152126, 176931, 204652, 235509, 269730, 307551, 349216
Offset: 1

Views

Author

James A. Record (james.record(AT)gmail.com), Nov 07 2004

Keywords

Examples

			There are no 1- or 2-gonal anti-diamonds, so 1 and (2n+2) are the first and second terms since all the sequences begin as such.
		

Crossrefs

Cf. A000578, A000447, A004466, A007588, A063521, A062523 - "polar" structured anti-diamonds; A100189 - "equatorial" structured meta-anti-diamond numbers; A006484 for other structured meta numbers; and A100145 for more on structured numbers.

Programs

  • Magma
    [(1/6)*(2*n^4-2*n^2+6*n): n in [1..40]]; // Vincenzo Librandi, Aug 18 2011
    
  • Mathematica
    Table[(2n^4-2n^2+6n)/6,{n,40}] (* or *) LinearRecurrence[{5,-10,10,-5,1}, {1,6,27,84,205},40] (* Harvey P. Dale, May 11 2016 *)
  • PARI
    vector(40, n, (n^4 -n^2 +3*n)/3) \\ G. C. Greubel, Nov 08 2018

Formula

a(n) = (1/6)*(2*n^4 - 2*n^2 + 6*n).
G.f.: x*(1 + x + 7*x^2 - x^3)/(1-x)^5. - Colin Barker, Apr 16 2012
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5); a(1)=1, a(2)=6, a(3)=27, a(4)=84, a(5)=205. - Harvey P. Dale, May 11 2016
E.g.f.: (3*x + 6*x^2 + 6*x^3 + x^4)*exp(x)/3. - G. C. Greubel, Nov 08 2018

A063569 6^a(n) is smallest positive power of 6 containing the string 'n'.

Original entry on oeis.org

9, 3, 3, 2, 6, 6, 1, 5, 12, 4, 9, 16, 4, 13, 28, 18, 3, 10, 15, 21, 26, 3, 22, 12, 27, 26, 17, 7, 16, 4, 13, 22, 24, 12, 27, 19, 2, 21, 22, 30, 13, 14, 22, 25, 17, 15, 6, 15, 28, 15, 21, 31, 46, 23, 28, 18, 6, 15, 20, 17, 10, 8, 11, 33, 14, 6, 6, 8, 18, 9, 11, 22, 26, 17, 16, 33
Offset: 0

Views

Author

Robert G. Wilson v, Aug 10 2001

Keywords

Crossrefs

Essentially the same as A062523.

Programs

  • Mathematica
    a = {}; Do[k = 1; While[ StringPosition[ ToString[6^k], ToString[n] ] == {}, k++ ]; a = Append[a, k], {n, 0, 60} ]; a
  • Python
    def A063569(n):
        m, k, s = 1, 6, str(n)
        while s not in str(k):
            m += 1
            k *= 6
        return m # Chai Wah Wu, Nov 14 2019

A176766 Smallest power of 6 whose decimal expansion contains n.

Original entry on oeis.org

10077696, 1, 216, 36, 46656, 46656, 6, 7776, 2176782336, 1296, 10077696, 2821109907456, 1296, 13060694016, 6140942214464815497216, 101559956668416, 216, 60466176, 470184984576, 21936950640377856, 170581728179578208256, 216
Offset: 0

Views

Author

Jonathan Vos Post, Apr 25 2010

Keywords

Comments

This is to 6 as A176763 is to 3 and as A030001 is to 2.

Examples

			a(1) = 1 because 6^0 = 1 has "1" as a substring (not a proper substring, though).
a(2) = 216 because 6^3 = 216 has "2" as a substring.
a(3) = 36 because 6^2 = 36 has "3" as a substring.
		

Crossrefs

Programs

  • Mathematica
    A176766[n_] := Block[{k = -1}, While[StringFreeQ[IntegerString[6^++k], IntegerString[n]]]; 6^k]; Array[A176766, 50, 0] (* Paolo Xausa, Apr 03 2024 *)

Formula

a(n) = MIN{A000400(i) such that n in decimal representation is a substring of A000400(i)}.
a(n) = 6^A062523(n). - Michel Marcus, Sep 30 2014

Extensions

Corrected and extended by Sean A. Irvine and Jon E. Schoenfield, May 05 2010
a(0) prepended by Paolo Xausa, Apr 03 2024
Showing 1-3 of 3 results.