

A104623


Indices of semiprime (A001358) values of HeptanacciLucas numbers A104621.


2



4, 8, 9, 11, 12, 14, 15, 16, 22, 23, 32, 34, 37, 41, 42, 50, 52, 57, 58, 66, 69, 76, 77, 81, 90, 120, 139
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OFFSET

0,1


COMMENTS

The 7thorder linear recurrence A104622 (heptanacciLucas numbers) is a generalization of the Lucas sequence A000032. T. D. Noe and I have noted that the heptanacciLucas numbers have many more primes than the corresponding heptanacci (see A104414) which he found has only the first 3 primes that I identified through the first 5000 values, whereas these heptanacciLucas numbers have 17 primes among the first 100 values. For primes in HeptanacciLucas numbers, see A104622.


LINKS

Table of n, a(n) for n=0..26.
Mario Catalani, Polymatrix and Generalized Polynacci Numbers, arXiv:math.CO/0210201 v1, 2002
Eric Weisstein's World of Mathematics, Semiprime.


EXAMPLE

A104621(4) = 15 = 3 * 5,
A104621(8) = 247 = 13 * 19,
A104621(9) = 493 = 17 * 29,
A104621(11) = 1959 = 3 * 653,
A104621(12) = 3903 = 3 * 1301,
A104621(14) = 15487 = 17 * 911,


CROSSREFS

Cf. A001358.
Sequence in context: A118715 A175839 A226085 * A228653 A158758 A229004
Adjacent sequences: A104620 A104621 A104622 * A104624 A104625 A104626


KEYWORD

nonn


AUTHOR

Jonathan Vos Post, Mar 17 2005


STATUS

approved



