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A058820 a(0) = 1, a(1) = 5; for n >= 2 a(n) is the number of degree-n monic reducible polynomials over GF(5), i.e., a(n) = 5^n - A001692(n). 0
1, 5, 15, 85, 475, 2501, 13045, 66965, 341875, 1736125, 8789377, 44389205, 223796925, 1126802885, 5667555805, 28483073133, 143051171875, 718060661765, 3602769749125, 18069618626645, 90599060546905, 454130626863845, 2275813711825285, 11402627696161685, 57121117919938125 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Dimensions of homogeneous subspaces of shuffle algebra over 5-letter alphabet (see A058766 for 2-letter case).

REFERENCES

M. Lothaire, Combinatorics on words, Cambridge mathematical library, 1983, p. 126 (definition of shuffle algebra).

LINKS

Table of n, a(n) for n=0..24.

PROG

(PARI) a(n) = if (n<=1, 5^n, 5^n - sumdiv(n, d, moebius(d)*5^(n/d))/n); \\ Michel Marcus, Oct 30 2017

CROSSREFS

Cf. A001692, A058766.

Sequence in context: A030487 A165470 A165625 * A054363 A211944 A336998

Adjacent sequences:  A058817 A058818 A058819 * A058821 A058822 A058823

KEYWORD

nonn

AUTHOR

Claude Lenormand (claude.lenormand(AT)free.fr), Jan 04 2001

EXTENSIONS

Better description from Sharon Sela (sharonsela(AT)hotmail.com), Feb 19 2002

More terms from Michel Marcus, Oct 30 2017

STATUS

approved

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Last modified January 23 03:15 EST 2022. Contains 350504 sequences. (Running on oeis4.)