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A055261
Sums of two powers of 16.
5
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
OFFSET
1,1
LINKS
FORMULA
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).
EXAMPLE
a(4) = 272 = 16^2+16^1.
MAPLE
A055261:= proc(n)
local p1, p2;
p1:= floor((sqrt(8*n-7)-1)/2);
p2:= n - 1 - p1*(p1+1)/2;
16^p1 + 16^p2
end proc; # Robert Israel, Apr 07 2014
CROSSREFS
Cf. A052216.
Sequence in context: A212740 A212742 A178145 * A307690 A100294 A192453
KEYWORD
base,easy,nonn,tabl
AUTHOR
Henry Bottomley, Jun 22 2000
STATUS
approved