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A055261
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Sums of two powers of 16.
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5
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2, 17, 32, 257, 272, 512, 4097, 4112, 4352, 8192, 65537, 65552, 65792, 69632, 131072, 1048577, 1048592, 1048832, 1052672, 1114112, 2097152, 16777217, 16777232, 16777472, 16781312, 16842752, 17825792, 33554432, 268435457
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = 16^(n-trinv(n))+16^trinv(n), where trinv(n) = floor((1+sqrt(1+8*n))/2) = A002262(n) and n-trinv(n) = A003056(n).
Regarded as a triangle T(n, k)=16^n+16^k, so as a sequence a(n) =16^A002262(n)+16^A003056(n).
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EXAMPLE
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a(4) = 272 = 16^2+16^1.
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MAPLE
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local p1, p2;
p1:= floor((sqrt(8*n-7)-1)/2);
p2:= n - 1 - p1*(p1+1)/2;
16^p1 + 16^p2
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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