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A118234 Column 3 of triangle A118233, starting at row 1 to include leading zeros. 0
0, 0, 1, 2, 0, 3, 2, 2, 3, 6, 1, 7, 3, 3, 5, 10, 2, 11, 5, 5, 7, 14, 3, 13, 7, 8, 7, 18, 3, 19, 10, 9, 11, 15, 5, 23, 11, 11, 11, 26, 5, 27, 13, 11, 15, 30, 7, 27, 13, 15, 15, 34, 8, 27, 15, 17, 19, 38, 7, 39, 19, 17, 21, 31, 9, 43, 21, 21, 15, 46, 11, 47, 23, 19, 23, 39, 11, 51, 21, 26, 27 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..81.

FORMULA

a(3*n-1) = eulerphi(3*n)/2 - 1.

PROG

(PARI) {a(n)=local(M=matrix(n+2, n+2, r, c, if(r>=c, if(gcd(r-c+1, c)==1, 1, 0)))^2); M[n, 3]}

CROSSREFS

Cf. A118233.

Sequence in context: A152164 A263112 A110493 * A262771 A152039 A180196

Adjacent sequences:  A118231 A118232 A118233 * A118235 A118236 A118237

KEYWORD

nonn

AUTHOR

Leroy Quet, Paul D. Hanna, Apr 16 2006

STATUS

approved

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Last modified December 4 17:26 EST 2016. Contains 278755 sequences.