OFFSET
0,2
LINKS
EXAMPLE
n = 10: row 11 of A070165 = [11,34,17,52,26,13,40,20,10,5,16,8,4,2,1],
therefore A070165(11,9) = 10 and a(10) = 11;
n = 11: rows 12 and 13 of A070165 don't contain 11, but 14 does:
row 12: [12,6,3,10,5,16,8,4,2,1],
row 13: [13,40,20,10,5,16,8,4,2,1],
row 14: [14,7,22,11,34,17,52,26,13,40,20,10,5,16,8,4,2,1],
therefore A070165(14,4) = 11: a(11) = 14.
MATHEMATICA
mcollQ[n_, k_]:=MemberQ[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&], k]==True; Prepend[Table[i=n+1; While[!mcollQ[i, n], i++]; i, {n, 64}], 1] (* Jayanta Basu, May 27 2013 *)
Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; Join[{1}, Table[k = n + 1; While[! MemberQ[Collatz[k], n], k++]; k, {n, 100}]] (* T. D. Noe, May 28 2013 *)
PROG
(Haskell)
import Data.List (find)
import Data.Maybe (fromJust)
a187831 0 = 1
a187831 n = head $ fromJust $
find (n `elem`) $ drop (fromIntegral n) a070165_tabf
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jan 04 2013
STATUS
approved