id:A152455 - OEIS Search Results

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a(n) = minimal integer m such that there exists an m X m integer matrix of order n.

+0
2

0, 1, 2, 2, 4, 2, 6, 4, 6, 4, 10, 4, 12, 6, 6, 8, 16, 6, 18, 6, 8, 10, 22, 6, 20, 12, 18, 8, 28, 6, 30, 16, 12, 16, 10, 8, 36, 18, 14, 8, 40, 8, 42, 12, 10, 22, 46, 10, 42, 20, 18, 14, 52, 18, 14, 10, 20, 28, 58, 8, 60, 30, 12, 32, 16, 12, 66, 18, 24, 10, 70, 10, 72, 36, 22, 20, 16, 14 (list; graph; listen)

	OFFSET	`1,3`
	FORMULA	`a(1)=0, a(2)=1. If n mod 4 eq 2 then a(n)=a(n/2).` `Otherwise a(n) = sum (pi-1)pi^(ei-1) where n = p1^e1p2^e2*...pk^ek is prime factorization of n.`
	PROGRAM	`(MAGMA) a := function(n)` `if n le 2 then return n-1; end if;` `if n mod 4 eq 2 then n := n div 2; end if;` `f := Factorization(n);` `return &+[(t[1]-1)*t[1]^(t[2]-1):t in f];` `end function;`
	CROSSREFS	`See A080737 for another version. - N. J. A. Sloane (njas(AT)research.att.com), Dec 05 2008` `Adjacent sequences: A152452 A152453 A152454 this_sequence A152456 A152457 A152458` `Sequence in context: A096504 A011773 A080737 this_sequence A000010 A003978 A122645`
	KEYWORD	`easy,nonn`
	AUTHOR	`W. R. Unger (billu(AT)maths.usyd.edu.au), Dec 04 2008`

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Last modified November 7 16:45 EST 2009. Contains 166093 sequences.

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