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.

A082209 a(1) = 1, a(n) = smallest number such that the concatenation of a(n-1) and a(n) is a square.

Original entry on oeis.org

1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61, 504, 1, 6, 4, 9, 61
Offset: 1

Views

Author

Amarnath Murthy, Apr 10 2003

Keywords

Examples

			a(4) = 9 hence a(5) = 61 and 961 = 31^2.
		

Crossrefs

Cf. A082210.
See A090566 for another version.

Programs

  • Magma
    &cat [[1,6,4,9,61,504]: n in [0..20]]; // Vincenzo Librandi, Nov 23 2015
    
  • Mathematica
    PadRight[{},120,{1,6,4,9,61,504}] (* Harvey P. Dale, May 04 2013 *)
    LinearRecurrence[{0, 0, 0, 0, 0, 1},{1, 6, 4, 9, 61, 504},83] (* Ray Chandler, Aug 26 2015 *)
    CoefficientList[ Series[ (504x^5 + 61x^4 + 9x^3 + 4x^2 + 6x + 1)/(1 - x^6), {x, 0, 83}], x] (* Robert G. Wilson v, Nov 22 2015 *)
  • PARI
    A082209(n)=[1, 6, 4, 9, 61, 504][(n-1)%6+1] \\ M. F. Hasler, Nov 24 2015

Formula

Periodic with period 6. - Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 20 2003

Extensions

Corrected and extended by Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 20 2003

A090567 Squares arising in A082209.

Original entry on oeis.org

16, 64, 49, 961, 61504, 5041, 16, 64, 49, 961, 61504, 5041, 16, 64, 49, 961, 61504, 5041, 16, 64, 49, 961, 61504, 5041, 16, 64, 49, 961, 61504, 5041, 16, 64, 49, 961, 61504, 5041, 16, 64, 49, 961, 61504, 5041, 16, 64, 49, 961, 61504, 5041, 16, 64, 49
Offset: 1

Views

Author

Amarnath Murthy, Dec 11 2003

Keywords

Programs

Formula

a(n) = A082210(n+1)^2. - David Wasserman, Jan 05 2006

Extensions

Corrected and extended by David Wasserman, Jan 05 2006

A264775 Square root of concatenation(A090566(n), A090566(n+1)).

Original entry on oeis.org

4, 25, 159, 531, 3101, 24903, 243740, 433129, 2703038, 21046245, 53478992, 292123372, 2164833445, 21425610902, 48888908358, 192151648872, 477890021223, 2279013856319, 19998940546342, 46961100477911, 72630984382646, 259140398165389, 1861711571434526, 14850553878036591, 56672657547446354, 303286443000496342, 2448230500494961492, 4821616822771036069, 24316253937847771953
Offset: 1

Views

Author

M. F. Hasler, Nov 24 2015

Keywords

Comments

Sequence A090566 lists the smallest integer larger than the preceding term such that their concatenation is a square. This sequence lists the square root of these squares.
The initial term a(0)=1 corresponds to the natural extension A090566(0):=0 (or an "empty" A090566(0)).
Sequence A082210 is the analog of this corresponding to the variant A082209 of A090566.

Crossrefs

Showing 1-3 of 3 results.