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A101757 Indices of semiprime tribonacci numbers. 1
5, 12, 18, 42, 44, 50, 58, 67, 74, 83, 90, 95, 126, 142, 194, 210, 211, 275, 367, 382, 479, 655, 734, 818, 839, 926, 939, 1047 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..28.

Eric Weisstein's World of Mathematics, Semiprime

Eric Weisstein's World of Mathematics, Tribonacci Number

Index entries for linear recurrences with constant coefficients, signature (1, 1, 1).

FORMULA

A000073(a(n)) = A101758(n).

MATHEMATICA

Flatten[Position[LinearRecurrence[{1, 1, 1}, {1, 1, 2}, 100], _?(PrimeOmega[ #]==2&)]]+1 (* This generates the first 12 terms of the sequence.  To generate more, increase 100 to a higher number, but it will take increasingly long to run. *) (* Harvey P. Dale, May 31 2013 *)

CROSSREFS

Cf. A000073, A001358, A101758.

Sequence in context: A314290 A246300 A294143 * A174518 A109403 A093084

Adjacent sequences:  A101754 A101755 A101756 * A101758 A101759 A101760

KEYWORD

nonn,more

AUTHOR

Jonathan Vos Post and Ray Chandler, Dec 26 2004

EXTENSIONS

More terms from David Wasserman, Apr 03 2008

STATUS

approved

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Last modified May 25 03:14 EDT 2019. Contains 323539 sequences. (Running on oeis4.)