id:A051352 - OEIS Search Results

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a(0) = 0; for n>0, a(n) = a(n-1) + n if n not prime else a(n-1) - n.

+0
3

0, 1, -1, -4, 0, -5, 1, -6, 2, 11, 21, 10, 22, 9, 23, 38, 54, 37, 55, 36, 56, 77, 99, 76, 100, 125, 151, 178, 206, 177, 207, 176, 208, 241, 275, 310, 346, 309, 347, 386, 426, 385, 427, 384, 428, 473, 519, 472, 520, 569, 619, 670, 722, 669, 723, 778 (list; graph; listen)

	OFFSET	`0,4`
	COMMENT	`Sequence is not monotonic.` `a(n) = a(n-1)+n(1-2A010051(n)) = a(n-1)+n(2A0005171(n)-1) = a(n-1)+n*(A0005171(n)-A010051(n)). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 25 2009]`
	FORMULA	`Difference between sum of composite numbers and prime numbers <= n. - Zak Seidov (zakseidov(AT)yahoo.com), Sep 27 2003`
	CROSSREFS	`Sequence in context: A089389 A081550 A046779 this_sequence A003816 A083745 A019906` `Adjacent sequences: A051349 A051350 A051351 this_sequence A051353 A051354 A051355`
	KEYWORD	`sign,easy,nice,new`
	AUTHOR	`Armand Turpel armandt(AT)unforgettable.com`

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.

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