Table of n, a(n) for n=0..4.
Masao Koike, Modular forms on non-compact arithmetic triangle groups, Unpublished manuscript [Extensively annotated with OEIS A-numbers by N. J. A. Sloane, Feb 14 2021.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: A194454 A219384 A198955 * A063436 A010004 A172073
Adjacent sequences: A341560 A341561 A341562 * A341564 A341565 A341566
Robert C. Lyons, Feb 14 2021