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A299119
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Positive solution to 2^(n-1) = (1/n) * Sum_{d|n} a(d) * a(n/d).
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5
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1, 2, 6, 14, 40, 84, 224, 484, 1134, 2480, 5632, 12036, 26624, 56896, 122640, 261078, 557056, 1176876, 2490368, 5237360, 11008704, 23057408, 48234496, 100635144, 209714400, 436154368, 905962860, 1878931264, 3892314112, 8052800160, 16642998272, 34359209436
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OFFSET
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1,2
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COMMENTS
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LINKS
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MAPLE
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with(numtheory):
a:= proc(n) option remember; `if`(n=1, 1, n*2^(n-2)-
add(a(d)*a(n/d), d=divisors(n) minus {1, n})/2)
end:
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MATHEMATICA
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nn=50;
sys=Table[2^(n-1)*n==Sum[a[d]*a[n/d], {d, Divisors[n]}], {n, nn}];
Array[a, nn]/.Solve[sys, Array[a, nn]][[2]]
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CROSSREFS
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Cf. A000005, A000010, A000740, A001787, A018804, A023900, A029935, A034691, A046643, A059966, A228369, A257098, A296302, A298971, A299149, A299151.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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