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 1-2 of 2 results.

A193307 Number of 'Reverse and Subtract' steps needed to reach 0, or -1 if never reaches 0, using base -1+i and subtracting the original number from the reversed.

Original entry on oeis.org

0, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, 2, 15, -1, 1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 3, -1, 1, -1, 3, -1, 1, -1, 1, -1, 3, 2, -1, -1, 15, -1, -1, -1, -1, -1, 1, -1, 3, -1, -1, -1, 1, -1, 7, 2, -1, 2, -1, -1, -1, -1, -1, -1, 1, 14, 1, -1, -1, 6, -1, -1
Offset: 0

Views

Author

Kerry Mitchell, Jul 22 2011

Keywords

Examples

			Decimal 12 is 1100 in binary, which is 2+0i using complex base -1+i. Reversing 1100 gives 0011, or 0+i. Subtracting the original number from the reversed results in -2+i, or 11111 using the complex base. Its reversal is the same, so subtracting them gives 0. Decimal 12 took 2 steps to reach 0, so a(12) = 2.
		

Crossrefs

Cf. A193239 (number of steps needed to reach a palindrome with complex base -1+i).
Cf. A193306 (number of 'Reverse and Subtract' steps needed to reach 0, or -1 if never reaches 0, using base -1+i and subtracting the reversed number from the original).

A193505 Decimal expansion of bean curve area.

Original entry on oeis.org

1, 0, 5, 8, 0, 4, 9, 6, 2, 9, 1, 3, 6, 6, 2, 7, 0, 7, 9, 5, 1, 3, 2, 1, 2, 3, 1, 6, 9, 5, 7, 9, 2, 4, 1, 7, 7, 1, 6, 5, 7, 0, 5, 3, 1, 1, 3, 8, 7, 4, 3, 2, 0, 0, 2, 4, 1, 5, 7, 6, 6, 2, 1, 2, 3, 0, 9, 7, 3, 8, 5, 2, 2, 3, 2, 3, 7, 0, 6, 4, 3, 2, 1, 4, 9, 0, 7, 2, 9, 0, 9, 7, 9, 0, 3, 6, 8, 4, 3, 1, 8, 3, 2, 7, 9
Offset: 1

Views

Author

Jean-François Alcover, Jul 29 2011

Keywords

Comments

area = 7*Pi/(12*sqrt(3)). - Eric W. Weisstein, Feb 05 2018

Examples

			1.058049629...
		

Crossrefs

Cf. A193306 (arc length).

Programs

  • Mathematica
    area = Sqrt[2] NIntegrate[Sqrt[x (1 - x + Sqrt[1 + (2 - 3 x) x])], {x, 0, 1}, WorkingPrecision -> 120]; Take[RealDigits[area][[1]], 105]
    RealDigits[7 Pi/(12 Sqrt[3]), 10, 105][[1]] (* Eric W. Weisstein, Feb 05 2018 *)
Showing 1-2 of 2 results.