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A144751
a(1) = 3, a(n + 1) = 1 + a(n) + least odd prime factor of a(n).
1
3, 7, 15, 19, 39, 43, 87, 91, 99, 103, 207, 211, 423, 427, 435, 439, 879, 883, 1767, 1771, 1779, 1783, 3567, 3571, 7143, 7147, 7155, 7159, 14319, 14323, 28647, 28651, 28659, 28663, 57327, 57331, 114663, 114667, 114675, 114679, 229359
OFFSET
1,1
COMMENTS
The conjectured g.f. (-4*x^11 + 12*x^10 + 8*x^9 + 24*x^8 + 56*x^7 + 72*x^6 + 43*x^5 + 39*x^4 + 19*x^3 + 15*x^2 + 7*x + 3)/(4*x^12 - 5*x^6 + 1) is wrong; it matches only the first 41 terms of the sequence [R. J. Mathar, Jun 16 2009]
MATHEMATICA
vec=NestList[ #+1+Cases[ FactorInteger[ # ][ [ All, 1 ] ], _?OddQ, 1, 1 ][ [ 1 ] ]&, 3, 100 ]
NestList[1+#+Select[FactorInteger[#][[All, 1]], OddQ][[1]]&, 3, 40] (* Harvey P. Dale, Oct 08 2016 *)
CROSSREFS
Equals A140525 + 1.
Sequence in context: A186300 A323650 A350696 * A138847 A235699 A077777
KEYWORD
nonn
AUTHOR
Peter Pein, Feb 09 2009
STATUS
approved