Template:Sequence of the Day for April 12

Intended for: April 12, 2013

Timetable

• First draft entered by Alonso del Arte on April 6, 2012 ✓
• Draft reviewed by Daniel Forgues onApril 13, 2016 ✓
• Draft to be approved by March 12, 2013

Yesterday's SOTD * Tomorrow's SOTD

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A065442: Decimal expansion of the Erdős–Borwein constant

∑ ∞ k  = 1   1 2 k  −  1

.

1.60669515241529...

In 1948, Paul Erdős proved that this number is irrational. We can't say for sure if the related number

∑ ∞ k  = 1   χp (2 k  −  1) 2 k  −  1

(see A173898) is also irrational. (  

χp(n)

is the characteristic function of the primes).