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 1-4 of 4 results.

A061361 a(1) = 4; a(n) = least number such that the concatenation a(n)a(n-1)...a(2)a(1) is a square.

Original entry on oeis.org

4, 6, 17, 604, 9612, 85848855, 109457393440691436, 16484027824615378535694780556419522, 2537811713051483817817710620248313487995814710180147690293469081793581
Offset: 1

Views

Author

Amarnath Murthy, Apr 28 2001

Keywords

Examples

			a(3)a(2)a(1) = 1764 = 42^2, a(4)a(3)a(2)a(1) = 6041764 = 2458^2, a(5)a(4)a(3)a(2)a(1) = 8584885596126041764 = 2929997542^2.

Crossrefs

Cf. A050636, A050637, A061359, A061363.

Extensions

Corrected by Larry Reeves (larryr(AT)acm.org), May 07 2001
More terms from Ulrich Schimke (ulrschimke(AT)aol.com), Nov 06 2001

A061491 a(1) = 1, a(n) = least number such that the concatenation a(n)a(n-1)...a(1) is a cube.

Original entry on oeis.org

1, 133, 100330363, 100000000300330000300660363, 100000000000000000000000000300000000300330000000000000300000000600660000300660363
Offset: 1

Views

Author

Amarnath Murthy, May 06 2001

Keywords

Examples

			a(1) = 1, a(2) = 133, a(2)a(1) = 1331 = 11^3.

Links

Crossrefs

Cf. A061359, A061361, A061363.

Programs

  • Maple
    f:= proc(n) local j; 10^(-3^(n-1)/2-1)*(add(10^(3^j/2),j=0..n-1)^3 - add(10^(3^j/2),j=0..n-2)^3) end proc:
seq(f(n),n=1..5); # Robert Israel, Jun 17 2024

Formula

a(n) = 10^(-3^(n-1)/2-1)*(Sum_{j=0..n-1}(10^(3^j/2))^3 - Sum_{j=0..n-2} (10^(3^j/2))^3). - Robert Israel, Jun 17 2024

Extensions

More terms from Ulrich Schimke (ulrschimke(AT)aol.com), Nov 06 2001
Corrected by Robert Israel, Jun 17 2024

A065787 a(1) = 49; for n > 1, a(n) is the smallest integer > 0 such that the concatenation a(n)a(n-1)...a(2)a(1) is a square.

Original entry on oeis.org

49, 18, 167, 2401, 4086461727, 14079962896835441528, 309880704108832516500624685064706000856, 4681896102766617737298881383797502847166028831212571921983062786215145771871779
Offset: 1

Views

Author

Klaus Brockhaus, Nov 19 2001

Keywords

Comments

a(n) = A061363(n+1) for n > 1.

Crossrefs

Cf. A061359, A061363, A065691, A065785, A065786.

A061492 a(1) = 8, a(n) = least number such that the concatenation a(n)a(n-1)...a(1) is a cube.

Original entry on oeis.org

8, 172, 1585108, 4768417578272894, 931322574615480750806365966798663150842303643
Offset: 1

Views

Author

Amarnath Murthy, May 06 2001

Keywords

Examples

			a(1) = 8, a(2) = 172, a(2)a(1) = 1728 = 12^3.

Crossrefs

Cf. A061359, A061361, A061363, A061491.

Extensions

Corrected and extended by Ulrich Schimke (ulrschimke(AT)aol.com), Nov 06 2001. Next element has 135 digits.
Showing 1-4 of 4 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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