%I A000114
%S A000114 3,4,6,12,12,24,24,36,36,60,48,84,72,96,96,144,108,180,144,
%T A000114 192,180,264,192,300,252,324,288,420,288,480,384,480,432,
%U A000114 576,432,684,540,672,576,840,576,924,720,864,792,1104,768
%N A000114 Number of cusps of principal congruence subgroup GAMMA^{hat}(n).
%C A000114 A001766(n)=n*a(n). - Michael Somos Jan 29 2004
%D A000114 R. A. Rankin, Modular Forms and Functions, Cambridge 1977, p. 62.
%p A000114 A000114 := proc(n) local b,d: if n = 2 then RETURN(3); else b := n^2/
               2; for d from 1 to n do if irem(n,d) = 0 and isprime(d) then b := 
               b*(1-d^(-2)); fi; od; RETURN(b); fi: end:
%Y A000114 Sequence in context: A062822 A175029 A113728 this_sequence A136243 A051592 
               A044843
%Y A000114 Adjacent sequences: A000111 A000112 A000113 this_sequence A000115 A000116 
               A000117
%K A000114 nonn,easy
%O A000114 2,1
%A A000114 N. J. A. Sloane (njas(AT)research.att.com).