Table of n, a(n) for n=0..6.
Masao Koike, Modular forms on non-compact arithmetic triangle groups, Unpublished manuscript [Extensively annotated with OEIS A-numbers by N. J. A. Sloane, Feb 14 2021. Sloane wrote 2005 on the first page but the internal evidence suggests 1997.] See page 30.
Sequence in context: A186210 A209676 A000735 * A022704 A060785 A059986
Adjacent sequences: A341555 A341556 A341557 * A341559 A341560 A341561
Robert C. Lyons, Feb 14 2021