A050765 Composite n added to sum of its prime factors is nextprime(n).

38400, 59290, 89700, 93639, 155952, 356400, 682080, 1226907, 1468320, 1648640, 2592000, 2995200, 3595500, 3933644, 5845203, 5967360, 8860995, 8953560, 9748480, 11351340, 12819224, 13226976, 13712490, 16193520, 18375000, 19294436, 21206016, 25259520, 28297500

Offset: 1

Author

Patrick De Geest, Sep 15 1999

Keywords

• nonn
• nice

Examples

			nextprime(93639) = 93639 + (3+7+7+7+7+13) = 93683.
		

Links

• Donovan Johnson and Giovanni Resta, Table of n, a(n) for n = 1..1033 (terms < 10^12, first 500 terms from Donovan Johnson)
• C. Rivera, See also related puzzle

Crossrefs

Cf. A050766, A050703, A050710, A105779, A235425.

Programs

Mathematica

Reap[For[n = 4, n <= 2*10^7, n = If[PrimeQ[n+1], n+2, n+1], If[n + Total[Times @@@ FactorInteger[n] ] == NextPrime[n], Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Oct 18 2013 *)
cspfQ[n_]:=CompositeQ[n]&&NextPrime[n]==n+Total[Flatten[Table[ #[[1]], #[[2]]] &/@FactorInteger[n]]]; Select[Range[29*10^6],cspfQ] (* Harvey P. Dale, Oct 14 2017 *)

Extensions

Offset corrected by Donovan Johnson, Oct 18 2013