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n(n+1)/2 also exists as a simple direct method of summing a series of 1..n. There's no similar (obvious) shortcut for n! (I don't count lgamma as obvious...)
by alexkus 14y ago
n(n+1)/2 also exists as a simple direct method of summing a series of 1..n. There's no similar (obvious) shortcut for n!
(I don't count lgamma as obvious...)
- daniel-cussen 14y agoAnd n(n+1)/2 was only obvious to Euler!
- sesqu 14y agoHardly. It's a simple equation that has been independently discovered for as long as we've had algebra.
- daniel-cussen 14y agoThat's not the same as being obvious. Obvious means clear at first sight, or clear to a child. If you have to work for it, it's not obvious.
- sesqu 14y agoIt was clear to me as a child of maybe 8. Granted, in this day and age it's much easier to come up with elementary math, but I would say that particular equation meets the obviousness criterion of patent law, based on the aforementioned historical evidence.