A154365 Numbers n such that the smallest prime factor of composite(n) + the largest prime factor of composite(n) is prime and the sum of prime factors (with multiplicity) of composite(n) is prime.

2, 5, 6, 13, 22, 27, 32, 37, 41, 57, 59, 64, 65, 71, 79, 87, 103, 107, 135, 152, 155, 166, 196, 215, 235, 237, 253, 261, 286, 287, 306, 307, 316, 348, 366, 372, 373, 386, 393, 404, 423, 438, 448, 459, 490, 507, 524, 539, 568, 577, 586, 591, 632, 653, 668, 669

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

lpfQ[{n_, c_}]:=Module[{f=FactorInteger[c]}, PrimeQ[f[[1, 1]]+f[[-1, 1]]] && PrimeQ[Total[Flatten[Table[#[[1]], #[[2]]]&/@f]]]]; Module[{cmps=Select[ Range[1000], CompositeQ], len}, len=Length[cmps]; Select[Thread[ {Range[ len], cmps}], lpfQ]][[All, 1]] (* Harvey P. Dale, Aug 16 2020 *)

Crossrefs

Sequence in context: A038191 A321472 A087128 * A247959 A243799 A029544

Adjacent sequences: A154362 A154363 A154364 * A154366 A154367 A154368

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Jan 08 2009

Extensions

Edited and extended by Charles R Greathouse IV, Mar 31 2010

Status

approved