login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A117762 a(1) = 6; for n>1, a(n) = prime(n)*(prime(n)^2 - 1)/2. 9
6, 12, 60, 168, 660, 1092, 2448, 3420, 6072, 12180, 14880, 25308, 34440, 39732, 51888, 74412, 102660, 113460, 150348, 178920, 194472, 246480, 285852, 352440, 456288, 515100, 546312, 612468, 647460, 721392, 1024128, 1123980, 1285608, 1342740, 1653900 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(n) is the order of the matrix group PSL(2,prime(n)). - corrected by Tom Edgar, Sep 28 2015
REFERENCES
Blyth and Robertson, Essential Student Algebra, Volume 5: Groups,Chapman and Hall, New York, page 14
LINKS
FORMULA
a(n) = A127918(n), n>1.
a(n) = A000040(n)*A084921(n). - R. J. Mathar, Jan 29 2024
MATHEMATICA
a[n_]= If[n==1, 6, Prime[n]*(Prime[n]^2 -1)/2];
Table[a[n], {n, 40}]
Join[{6}, Table[Prime[n] (Prime[n]^2 - 1)/2, {n, 2, 40}]] (* Vincenzo Librandi, Sep 29 2015 *)
PROG
(PARI) a(n) = prime(n)*(prime(n)^2-1)/2;
vector(40, n, a(n+1)) \\ Altug Alkan, Sep 28 2015
(Magma) [6] cat [NthPrime(n)*(NthPrime(n)^2-1)/2: n in [2..40]]; // Vincenzo Librandi, Sep 29 2015
(SageMath)
def A117762(n): return nth_prime(n)*(nth_prime(n)^2-1)/2 + 3*int(n==1)
[A117762(n) for n in range(1, 41)] # G. C. Greubel, Jul 21 2023
CROSSREFS
Sequence in context: A093901 A334884 A334994 * A178957 A104362 A123900
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula, Apr 14 2006
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 22 22:43 EST 2024. Contains 370265 sequences. (Running on oeis4.)