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 A109056 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). 7
 1, 1, 4, 58, 3236, 713727, 627642640, 2205897096672, 31004442653082720, 1743005531132374350208 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS 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. 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; CROSSREFS Sequence in context: A216352 A295406 A229528 * A326944 A155204 A290765 Adjacent sequences:  A109053 A109054 A109055 * A109057 A109058 A109059 KEYWORD nonn AUTHOR Augustine O. Munagi, Jun 17 2005 STATUS approved

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Last modified March 29 20:20 EDT 2020. Contains 333117 sequences. (Running on oeis4.)