

A328359


Numbers k such that Omega(k  2) = Omega(k) = Omega(k + 2) where Omega = A001222.


2



5, 68, 93, 121, 143, 172, 185, 188, 203, 215, 217, 219, 244, 284, 289, 301, 303, 321, 342, 393, 404, 413, 415, 428, 436, 471, 490, 517, 535, 570, 581, 604, 669, 687, 697, 788, 791, 815, 858, 870, 892, 1014, 1057, 1079, 1135, 1137, 1139, 1147, 1167, 1205, 1206, 1208, 1210, 1255, 1268, 1276
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OFFSET

1,1


LINKS

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


EXAMPLE

5 is a term because A001222(3) = A001222(5) = A001222(7) = 1;
68 is a term because A001222(66) = A001222(68) = A001222(70) = 3;
93 is a term because A001222(91) = A001222(93) = A001222(95) = 2.


MATHEMATICA

Select[Range[10^4], PrimeOmega[#2]==PrimeOmega[#]==PrimeOmega[#+2]&] (* Metin Sariyar, Oct 14 2019 *)
Flatten[Position[Partition[PrimeOmega[Range[2000]], 5, 1], _?(#[[1]]== #[[3]] == #[[5]]&), 1, Heads>False]]+2 (* Harvey P. Dale, Nov 02 2021 *)


PROG

(MAGMA) [k: k in [4..1300] forall{m:m in [2, 2] &+[p[2]: p in Factorization(k+m)] eq &+[p[2]: p in Factorization(k)] }]; // Marius A. Burtea, Oct 15 2019


CROSSREFS

Cf. A001222, A280382, A278311.
Sequence in context: A129963 A115764 A252794 * A003361 A336433 A099334
Adjacent sequences: A328356 A328357 A328358 * A328360 A328361 A328362


KEYWORD

nonn


AUTHOR

JuriStepan Gerasimov, Oct 14 2019


STATUS

approved



