Did anyone try these?
+/2*1+i.21
462
+/2*i.22
462
Don Kelly
On 2017-08-29 6:17 AM, Murray Eisenberg wrote:
The sum in question is twice the sum of the integers from 1 to 21. By the
well-known formula (sometimes attributed to Gauss), the latter sum is half the
product of 21 and 21 + 1, so the sum in question is
*/21+i. 2
462
On28 Aug 2017 12:02:57 -0500,S kip Cave <[email protected]
<mailto:[email protected]>> wrote:
A simple problem posted on Quora:
What is the sum of all the even numbers from 2 to 42?
My J solution:
a=:>:i.42
+/(-.2|a)#a
462
I'm sure this can be done in a single line using a hook or fork.
but I'm not clear enough with the train rules to put this all together
on a single line.
Any suggestions?
——
Murray Eisenberg [email protected]
Mathematics & Statistics Dept.
Lederle Graduate Research Tower phone 240 246-7240 (H)
University of Massachusetts
710 North Pleasant Street
Amherst, MA 01003-9305
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