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Called the "Trice sequence" in C. A. Pickover's "Mazes of the Mind", 1992, p. 351.
George Grove, Beethoven and his Nine Symphonies (1896), reprinted by Dover Publications, Inc. New York
Table of n, a(n) for n=1..9.
Beethoven web site
Index entries for sequences based on music
Symphony No. 1 in C (Op. 21)
Symphony No. 2 in D (Op. 36)
Symphony No. 3 in E flat (Op. 55), Eroica
Symphony No. 4 in B flat (Op. 60)
Symphony No. 5 in C minor (Op. 67)
Symphony No. 6 in F (Op. 68), Pastoral
Symphony No. 7 in A (Op. 92),
Symphony No. 8 in F (Op. 93),
Symphony No. 9 in D minor (Op. 125), Choral
Sequence in context: A219919 A219215 A155710 * A112352 A168513 A067598
Adjacent sequences: A001488 A001489 A001490 * A001492 A001493 A001494
N. J. A. Sloane, GEIER(AT)LaDune.Westfalen.De (Michael Gierhake)
This was a mystery for many years - even Clifford Pickover could not recall the explanation. It was finally identified in 1998 by Derek Holt (dfh(AT)maths.warwick.ac.uk)
Additional comments from Neven Juric, Apr 15 2010