A226218 Ending primes for n-th composite number in the iterated procedure of composite added to sum of prime factors.

23, 11, 23, 23, 17, 19, 23, 23, 47, 41, 29, 31, 47, 47, 47, 41, 71, 71, 71, 83, 47, 53, 47, 71, 59, 71, 71, 83, 59, 167, 71, 59, 149, 167, 71, 167, 83, 71, 167, 79, 89, 251, 167, 149, 149, 83, 269, 89, 167, 251, 251, 113, 239, 149, 167, 109, 127, 269, 251, 107

Offset

1,1

Comments

If we consider nonprimes instead of composite then a(1)=2. Sorted list of primes generated here are given in A050778.

Links

Table of n, a(n) for n=1..60.

Example

For the first composite number 4 repeated application of composite added to sum of prime factors give 4, 8, 14, 23 and so a(1)=23.

Mathematica

a[n_] := NestWhile[#+Total[Times@@@FactorInteger[#]]&, n, !PrimeQ[#]&]; t={}; Do[If[!PrimeQ[n], AppendTo[t, a[n]]], {n, 4, 80}]; t

Crossrefs

Cf. A050703-A050710, A050778.

Sequence in context: A054574 A363371 A016837 * A294087 A323137 A083154

Adjacent sequences: A226215 A226216 A226217 * A226219 A226220 A226221

Keyword

nonn

Author

Jayanta Basu, May 31 2013

Status

approved