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A121544
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Sum of all proper base 4 numbers with n digits (those not beginning with 0).
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1
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6, 114, 1896, 30624, 491136, 7862784, 125822976, 2013241344, 32212156416, 515395682304, 8246335635456, 131941389041664, 2111062300164096, 33776997104615424, 540431954881806336, 8646911282940739584, 138350580546379186176, 2213609288819376390144
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OFFSET
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1,1
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COMMENTS
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Sum of the first 3*(4^(n-1)) integers starting with 4^(n-1).
Sum of the integers from 4^(n-1) to (4^n)-1.
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LINKS
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FORMULA
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a(n) = (4^(n-1) + 4^n - 1) * 3 * (4^(n-1))/2.
G.f.: -6*x*(x-1) / ((4*x-1)*(16*x-1)). - Colin Barker, Apr 30 2013
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EXAMPLE
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a(1) = 6 = 1 + 2 + 3.
a(2) = 114 = 10_4 + 11_4 + 12_4 + 13_4 + 20_4 + 21_4 + 22_4 + 23_4 + 30_4 + 31_4 + 32_4 + 33_4 = (4+5+6+7+8+9+10+11+12+13+14+15)_10.
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CROSSREFS
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KEYWORD
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easy,nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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