login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A105593 Number of steps for n to join the main line of A003508. 2

%I #8 May 22 2013 15:11:43

%S 0,0,0,0,2,1,0,0,3,1,0,0,2,1,1,7,1,0,6,5,7,2,1,0,8,1,8,4,1,0,7,6,5,4,

%T 5,1,4,3,5,5,0,0,12,11,4,1,5,4,11,11,1,10,4,3,0,4,10,10,3,2,10,9,2,11,

%U 2,3,10,9,9,2,1,0,2,1,2,1,9,0,10,9,2,2,2,1,1,5,7,8,10,9,23,4,7,4,7,8,0,0,1

%N Number of steps for n to join the main line of A003508.

%C a(n)=0 if n is a member of A003508. First term whose value is in question is 393.

%e a(5)=2 because 5=>6=>12 and 12 is the eighth term of A003508.

%t a[1] = 1; a[n_] := a[n] = a[n - 1] + 1 + Plus @@ Select[ Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[a[n - 1]]], # < a[n - 1] &]; Table[a[n], {n, 100}]; f[n_] := Module[{b, k = 1, t = Table[a[i], {i, 100}]}, b[1] = n; b[m_] := b[m] = b[m - 1] + 1 + Plus @@ Select[ Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[b[ m - 1]]], # < b[m - 1] &]; While[ Position[t, b[k]] == {}, k++ ]; k - 1]; Table[ f[n], {n, 105}]

%Y Cf. A003508.

%K nonn

%O 1,5

%A _R. K. Guy_ and _Robert G. Wilson v_, Apr 13 2005

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 14:02 EDT 2024. Contains 371254 sequences. (Running on oeis4.)