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Search: id:A056139
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A056139 n^2-primefloor[n]*primeceiling[n]. +0
3
0, 0, 1, 0, 1, 0, -13, 4, 23, 0, 1, 0, -25, 4, 35, 0, 1, 0, -37, 4, 47, 0, -91, -42, 9, 62, 117, 0, 1, 0, -123, -58, 9, 78, 149, 0, -73, 4, 83, 0, 1, 0, -85, 4, 95, 0, -187, -90, 9 (list; graph; listen)
OFFSET

2,7

COMMENT

a(n)=0 iff n is prime

FORMULA

a(n)=n^2-A007917(n)*A007918(n) =A000290(n)-A030664(n)

EXAMPLE

a(3)=3^2-3*3=0, a(4)=4^2-3*5=1

CROSSREFS

Cf. A056140, A056141.

Adjacent sequences: A056136 A056137 A056138 this_sequence A056140 A056141 A056142

Sequence in context: A138965 A005602 A010219 this_sequence A106293 A046734 A123172

KEYWORD

easy,sign

AUTHOR

Henry Bottomley (se16(AT)btinternet.com), Jun 15 2000

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Last modified October 10 20:39 EDT 2008. Contains 144831 sequences.


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