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Masao Koike, Modular forms on non-compact arithmetic triangle groups, Unpublished manuscript [Extensively annotated with OEIS A-numbers by N. J. A. Sloane, Feb 14 2021.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 31.
Sequence in context: A341427 A024379 A134290 * A078761 A034967 A199352
Adjacent sequences: A341570 A341571 A341572 * A341574 A341575 A341576
Robert C. Lyons, Feb 15 2021