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A109056
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To compute a(n) we first write down 4^n 1's in a row. Each row takes the rightmost 4th part of the previous row and each element in it equals sum of the elements of the previous row starting with the first of the rightmost 4th part. The single element in the last row is a(n).
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7
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OFFSET
| 0,3
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EXAMPLE
| For example, for n=3 the array looks like this:
1..1.....1..1..1..1..1..1..1..1..1..1..1..1..1..1..1..1..1
............1..2..3..4..5..6..7..8..9.10.11.12.13.14.15.16
...............................................13.27.42.58
........................................................58
Therefore a(4)=58.
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MAPLE
| proc(n::nonnegint) local f, a; if n=0 or n=1 then return 1; end if; f:=L->[seq(add(L[i], i=3*nops(L)/4+1..j), j=3*nops(L)/4+1..nops(L))]; a:=f([seq(1, j=1..4^n)]); while nops(a)>4 do a:=f(a) end do; a[4]; end proc;
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CROSSREFS
| Sequence in context: A099348 A197177 A155668 * A155204 A144992 A198511
Adjacent sequences: A109053 A109054 A109055 * A109057 A109058 A109059
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KEYWORD
| nonn
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AUTHOR
| A. O. Munagi (amunagi(AT)yahoo.com), Jun 17 2005
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