Table of n, a(n) for n=0..5.
Masao Koike, Modular forms on non-compact arithmetic triangle groups, Unpublished manuscript [Extensively annotated with OEIS A-numbers by N. J. A. Sloane, Feb 14 2021.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: A042749 A219568 A202792 * A317337 A089036 A273033
Adjacent sequences: A341557 A341558 A341559 * A341561 A341562 A341563
Robert C. Lyons, Feb 14 2021