

A105572


Numbers m such that m3 and m+3 have 3 prime factors.


3



15, 47, 73, 95, 102, 113, 127, 150, 151, 167, 168, 185, 233, 239, 241, 258, 276, 282, 287, 289, 313, 319, 335, 360, 366, 407, 409, 415, 426, 431, 432, 433, 439, 480, 521, 527, 552, 558, 593, 599, 601, 606, 607, 612, 642, 648, 649, 654, 655, 660, 708, 713
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OFFSET

1,1


COMMENTS

Prime factors counted with multiplicity.  Harvey P. Dale, May 07 2023


LINKS



EXAMPLE

73  3 = 70 = 2 * 5 * 7 and 73 + 3 = 76 = 2 * 2 * 19 so 73 is in the sequence.
81  3 = 78 = 2 * 3 * 13 but 81 + 3 = 84 = 2 * 2 * 3 * 7 so 81 is not in the sequence. (End)


MATHEMATICA

q=3; lst={}; Do[If[Plus@@Last/@FactorInteger[nq]==q&&Plus@@Last/@FactorInteger[n+q]==q, AppendTo[lst, n]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Feb 01 2009 *)
Flatten[Position[Partition[PrimeOmega[Range[800]], 7, 1], _?(#[[1]]==#[[7]]==3&), 1, Heads> False]]+3 (* Harvey P. Dale, May 07 2023 *)


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



