

A178032


Numbers n such that n, n+1, n+2 are all of the form p*q^2 for distinct primes p,q.


4



603, 2523, 4203, 4923, 7442, 10467, 18027, 20402, 54475, 58923, 79011, 97675, 104211, 118323, 120787, 122571, 124891, 132723, 134307, 148075, 200491, 229707, 243602, 246571, 249307, 258507, 303651, 324331, 331387, 370827, 385675
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OFFSET

1,1


LINKS

Ray Chandler, Table of n, a(n) for n = 1..10000 (first 500 terms from Harvey P. Dale)
Index to sequences related to prime signature


EXAMPLE

603=3*3*67, 604=2*2*151, 605=5*11*11
2523=3*29*29, 2524=2*2*631, 2525=5*5*101


MATHEMATICA

SequencePosition[Table[If[Sort[FactorInteger[n][[All, 2]]]=={1, 2}, 1, 0], {n, 400000}], {1, 1, 1}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 30 2019 *)


PROG

(Sage) is_A178032 = lambda n: all(sorted(m for p, m in factor(k)) == [1, 2] for k in (n, n+1, n+2)) # [D. S. McNeil, Dec 17 2010]


CROSSREFS

Cf. A054753, A074172, A308683, A141621.
Sequence in context: A145331 A252957 A066785 * A107256 A177685 A250907
Adjacent sequences: A178029 A178030 A178031 * A178033 A178034 A178035


KEYWORD

nonn


AUTHOR

John L. Drost, Dec 16 2010


EXTENSIONS

Corrected and extended by D. S. McNeil, Dec 16 2010


STATUS

approved



