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

1,1

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

Example

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

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 *)

Crossrefs

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

Sequence in context: A248690 A342960 A050777 * A254852 A203792 A013873

Adjacent sequences: A050762 A050763 A050764 * A050766 A050767 A050768

Keyword

nonn,nice

Author

Patrick De Geest, Sep 15 1999

Extensions

Offset corrected by Donovan Johnson, Oct 18 2013

Status

approved