A080988 Define b by b(1) = 1 and for n>1, b(n) = b(n-1)+1/(3+1/b(n-1)); sequence gives numerator of b(n).
1, 5, 115, 57155, 13457544835, 718532108172999980195, 1987460976488531436231264449305834729789315, 14835338180729281137836887250133924105479472089418750626398379615457041439472496214755
Offset: 1
Examples
The sequence begins 1, 5/4, 115/76, 57155/31996, 13457544835/6509938156, ...
Programs
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Mathematica
NestList[#+1/(3+1/#)&,1,10]//Numerator (* Harvey P. Dale, Dec 13 2018 *)
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Reduce
a := 1; for i := 1:8 do write a := a+1/(3+1/a);
Formula
b[k]=n[k]/d[k]; n[1]=1, d[1]=1, m=3; for k>=2: n[k+1] = n[k] *(m*n[k] + 2*d[k]), d[k+1] = d[k] *(m*n[k] + d[k])
Comments