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1, 2, 3, 6, 7, 23, 19, 66, 95, 255, 187, 1059, 631, 3227, 5243, 11426, 7711, 51887, 27595, 184911, 232887, 606627, 364723, 2807935, 2405183, 8671943, 10368079, 36873651, 18512791, 167268639, 69273667, 496472226, 551130063, 1856103039
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| Row 6 of Pascal's triangle is: 1,6,15,20,15,6,1. The greatest common divisors of n and each integer from 1 to 6 are: GCD(1,6)=1, GCD(2,6)=2, GCD(3,6)=3, GCD(4,6)=2, GCD(5,6)=1, and GCD(6,6)=6. So a(6) = (1/6)*( 6*1 + 15*2 + 20*3 + 15*2 + 6*1 + 1*6) = 138/6 = 23. Note that each term of the sum in parentheses is a multiple of 6, so 138 is a multiple of 6.
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MAPLE
| A159068 := proc(n) add(binomial(n, k)*gcd(k, n), k=1..n) ; end: A159069 := proc(n) A159068(n)/n ; end: seq(A159069(n), n=1..80) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 06 2009]
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CROSSREFS
| A159068
Sequence in context: A050581 A073317 A064731 * A162681 A070301 A065536
Adjacent sequences: A159066 A159067 A159068 * A159070 A159071 A159072
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet, Apr 04 2009
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EXTENSIONS
| Extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 06 2009
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