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A105593 Number of steps for n to join the main line of A003508. 2
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, 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, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,5
COMMENTS
a(n)=0 if n is a member of A003508. First term whose value is in question is 393.
LINKS
EXAMPLE
a(5)=2 because 5=>6=>12 and 12 is the eighth term of A003508.
MATHEMATICA
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}]
CROSSREFS
Cf. A003508.
Sequence in context: A132013 A105820 A136263 * A029371 A114374 A111505
KEYWORD
nonn
AUTHOR
R. K. Guy and Robert G. Wilson v, Apr 13 2005
STATUS
approved

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Last modified June 20 22:01 EDT 2024. Contains 373532 sequences. (Running on oeis4.)