login
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.
1
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
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
KEYWORD
nonn,less
AUTHOR
EXTENSIONS
Edited and extended by Charles R Greathouse IV, Mar 31 2010
STATUS
approved