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A263510 Numbers n for which the numbers 6n+1, 3n+2, 6n+7 are all odd composite squarefree numbers, but none are semiprimes. 3
2121, 3011, 3963, 6125, 7631, 8173, 8275, 8649, 8781, 10519, 10851, 11383, 11599, 11883, 12001, 12163, 12271, 12789, 12807, 13749, 14509, 15381, 15705, 15959, 16583, 16761, 17163, 17473, 17787, 18813, 19283, 19831, 19937, 20483, 20513, 20633, 21673, 22121 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Peter J. C. Moses, Table of n, a(n) for n = 1..2000

MATHEMATICA

semiPrimeQ:=Last[Total[FactorInteger[#]]]==2&;

A263510=Select[Range[10000], Apply[And, Map[CompositeQ[#]&&OddQ[#]&&SquareFreeQ[#]&&(!semiPrimeQ[#])&, {6#+1, 3#+2, 6#+7}]]&]

CROSSREFS

Cf. A001358, A264778, A264779.

Sequence in context: A205660 A205949 A205460 * A250970 A238035 A248485

Adjacent sequences:  A263507 A263508 A263509 * A263511 A263512 A263513

KEYWORD

nonn

AUTHOR

Vladimir Shevelev and Peter J. C. Moses, Nov 24 2015

STATUS

approved

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Last modified June 20 11:38 EDT 2019. Contains 324234 sequences. (Running on oeis4.)