Template:Sequence of the Day for September 15

Intended for: September 15, 2011

Timetable

• First draft entered by Alonso del Arte on September 3, 2011 ✓
• Draft reviewed by Alonso del Arte on September 4, 2011 ✓
• Draft approved by Daniel Forgues September 15, 2012 ✓

Yesterday's SOTD * Tomorrow's SOTD

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A006752: Decimal expansion of Catalan’s constant

K   :=   ∑ ∞ i  = 0 ( − 1) i ( 2 i + 1) 2

 .

0.915965594177219...

We have known since antiquity that

2√  2

is irrational. The jury is still out on Catalan’s constant.