OFFSET
1,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..100
PROG
(GAP) Concatenation([1], List([2..20], n->Size(NormalSubgroups(GL(2, Integers mod n))))); # Andrew Howroyd, Jul 04 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Sharon Sela (sharonsela(AT)hotmail.com), Jan 07 2002
EXTENSIONS
Terms a(16) and beyond from Andrew Howroyd, Jul 04 2018
STATUS
approved