A064236 Number of decimal digits in A001042.

1, 1, 1, 1, 2, 3, 5, 10, 19, 38, 76, 152, 303, 605, 1210, 2420, 4839, 9678, 19355, 38709, 77417, 154834, 309667, 619333, 1238665, 2477330, 4954660, 9909319, 19818638, 39637275, 79274549

Offset: 0

Author

Jason Earls, Sep 22 2001

Keywords

• base
• nonn

Programs

Haskell

a064236 = length . show . a001042  -- Reinhard Zumkeller, Dec 16 2013

Mathematica

a[ 1 ] = 1; a[ 2 ] = 2; a[ n_ ] := a[ n ] = a[ n - 1 ]^2 - a[ n - 2 ]^2; Table[ Floor[ N[ Log[ 10, a[ n ] ], 36 ] ] + 1, {n, 1, 31} ]
IntegerLength[#]&/@(RecurrenceTable[{a[1]==1,a[2]==2,a[n]==a[n-1]^2- a[n-2]^2},a,{n,31}]) (* Harvey P. Dale, Dec 27 2013 *)

PARI

a(n) = if(n<2,n+1,a(n-1)^2-a(n-2)^2); l(n) = ln=0; while(n,n=floor(n/10); ln++); return(ln); for(n=0,21,print(l(a(n))))

Extensions

More terms from Robert G. Wilson v, Sep 24 2001