OFFSET
3,7
COMMENTS
Also the dimension of the space of cusp forms of weight two and level p, where p=5, 7, 11, 13, ... ranges over all primes exceeding 3. - Steven Finch, Apr 04 2007
The previous name was "Genus of Ono X0[p] points". - Felix Fröhlich, May 21 2021
LINKS
Ken Ono and Scott Ahlgren, Weierstrass points on X0(p) and supersingular j-invariants, Mathematische Annalen 325 (2003), 355-368, DOI:10.1007/s00208-002-0390-9.
FORMULA
From Felix Fröhlich, May 21 2021: (Start)
a(n) = A001617(prime(n)).
Let p = prime(n). Then
a(n) = (p-13)/12 if p == 1 (mod 12)
a(n) = (p-5)/12 if p == 5 (mod 12)
a(n) = (p-7)/12 if p == 7 (mod 12)
a(n) = (p+1)/12 if p == 11 (mod 12). (End)
MATHEMATICA
g[n_] := (Prime[n] - 13)/12 /; Mod[Prime[n], 12] - 1 == 0
g[n_] := (Prime[n] - 5)/12 /; Mod[Prime[n], 12] - 5 == 0
g[n_] := (Prime[n] - 7)/12 /; Mod[Prime[n], 12] - 7 == 0
g[n_] := (Prime[n] + 1)/12 /; Mod[Prime[n], 12] - 11 == 0
Table[g[n], {n, 3, 50}]
PROG
(PARI) a(n) = {my(p = prime(n), m = p % 12); if (m==1, (p-13)/12, if (m==5, (p-5)/12, if (m==7, (p-7)/12, if (m==11, (p+1)/12)))); } \\ Michel Marcus, Apr 06 2018
CROSSREFS
KEYWORD
nonn,uned,obsc
AUTHOR
Roger L. Bagula, Mar 17 2006
EXTENSIONS
Offset corrected by Michel Marcus, Apr 06 2018
Edited by Felix Fröhlich, May 21 2021
STATUS
approved