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A143268
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a(n) = phi(n)*T(n), where phi(n) is Euler's totient function (A000010) and T(n) = n*(n+1)/2 is the n-th triangular number (A000217).
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1
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1, 3, 12, 20, 60, 42, 168, 144, 270, 220, 660, 312, 1092, 630, 960, 1088, 2448, 1026, 3420, 1680, 2772, 2530, 6072, 2400, 6500, 4212, 6804, 4872, 12180, 3720, 14880, 8448, 11220, 9520, 15120, 7992, 25308, 13338, 18720, 13120, 34440, 10836, 39732
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = sum of n-th row of triangle A143267.
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EXAMPLE
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a(4) = 20 = phi(4) * T(4) = 2 * 10.
a(4) = 20 = sum of row 4 terms of triangle A143267: (2 + 4 + 6 + 8).
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MAPLE
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with(numtheory): seq((1/2)*n*(n+1)*phi(n), n=1..45); # Emeric Deutsch, Aug 23 2008
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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