OFFSET
1,1
COMMENTS
a(n) divides A244509(n).
For n>2 (i.e. p=prime(n)>=5), a(n) gives the order of the largest proper subgroup of GL(2,Z_p).
LINKS
Gregor Olsavsky, Groups formed from 2 X 2 matrices over Z_p, Mathematics Magazine, Vol. 63, No. 4 (Oct., 1990), pp. 269-272.
FORMULA
For n>1, a(n) = 2*p*(p^2-1) where p = prime(n).
For n>1, a(n) = 2*A127917(n).
MATHEMATICA
Prepend[2 Table[(Prime@ n + 1) Prime@ n (Prime@ n - 1), {n, 2, 34}], 6] (* Michael De Vlieger, Mar 24 2016, after Artur Jasinski at A127917 *)
PROG
(Sage) [6] + [2*p*(p^2-1) for p in prime_range(3, 150)]
(PARI) lista(nn) = {print1(6, ", "); forprime(p=3, nn, print1(2*p*(p^2-1), ", ")); } \\ Altug Alkan, Mar 24 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Tom Edgar, Mar 24 2016
STATUS
approved