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A280327
a(n) is obtained by applying the map k -> composite(k) n times, starting at n.
2
4, 12, 25, 39, 60, 94, 133, 183, 236, 320, 415, 520, 640, 805, 1007, 1212, 1463, 1800, 2144, 2562, 3021, 3523, 4135, 4840, 5747, 6630, 7701, 9057, 10392, 11812, 13519, 15400, 17534, 19827, 22564, 25624, 29206, 32998, 37041, 41819, 46659, 53223, 59345, 66104, 73368, 81897, 91157, 100827, 112045
OFFSET
1,1
EXAMPLE
a(3) is 25 because the third composite is 8, the eighth composite is 15, and for the 3rd iteration, the fifteenth composite is 25.
To get a(4): 4 -> 9 -> 16 -> 26 -> 39.
MATHEMATICA
c = Select[Range[10^6], CompositeQ]; Table[Nest[c[[#]] &, n, n], {n, 50}] (* Michael De Vlieger, Dec 31 2016 *)
CROSSREFS
Cf. A002808.
For primes, see A058009.
Sequence in context: A114979 A301042 A301062 * A008073 A301049 A008097
KEYWORD
nonn
AUTHOR
Matthew Campbell, Dec 31 2016
EXTENSIONS
More terms from Michael De Vlieger, Dec 31 2016
STATUS
approved