The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A226985 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A226985

Sum of inverse of increasing integers with a difference of 0, 1, 2, 3, ...: 1 + 1/2 + 1/4 + 1/7 + 1/11 + 1/16 + 1/22 + 1/29 + 1/37 + ....
(history; published version)

#28 by Charles R Greathouse IV at Sat Nov 11 13:39:33 EST 2017

STATUS

proposed

approved

#27 by Amiram Eldar at Sat Nov 11 13:02:25 EST 2017

STATUS

editing

proposed

#26 by Amiram Eldar at Sat Nov 11 13:00:57 EST 2017

CROSSREFS

Cf. A000124.

STATUS

approved

editing

Discussion

Sat Nov 11

13:02

Amiram Eldar: Add xref to the sequence in the Name (the Lazy Caterer's sequence).

#25 by Alois P. Heinz at Mon Sep 09 19:34:19 EDT 2013

STATUS

editing

approved

#24 by Alois P. Heinz at Mon Sep 09 19:34:06 EDT 2013

COMMENTS

We can note that tanh(sqrt(7)*piPi/2) = 0.9995... which is close to 1 by 0.05% so this constant is very close to 2*piPi/sqrt(7). - Didier Guillet, Jul 12 2013

FORMULA

Sum_{k >= 1} 1/(1+k*(k-1)/2).

STATUS

approved

editing

#23 by T. D. Noe at Sat Jul 13 11:10:47 EDT 2013

STATUS

proposed

approved

#22 by T. D. Noe at Fri Jul 12 23:42:18 EDT 2013

STATUS

editing

proposed

#21 by T. D. Noe at Fri Jul 12 23:42:13 EDT 2013

COMMENTS

We can note that tanh(sqrt(7)*pi/2) = 0,.9995... which is close to 1 by 0,.05 % so this constant is very close to 2*pi/sqrt(7). - Didier Guillet, Jul 12 2013

STATUS

proposed

editing

#20 by Didier Guillet at Fri Jul 12 15:21:52 EDT 2013

STATUS

editing

proposed

#19 by Didier Guillet at Fri Jul 12 15:21:39 EDT 2013

COMMENTS

We can note that tanh(sqrt(7)*pi/2)=0,9995... which is close to 1 by 0,05 % so this constant is very close to 2*pi/sqrt(7). - _Didier Guillet_, Jul 12 2013