This site is supported by donations to The OEIS Foundation.

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

 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. 4
 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. MATHEMATICA f[n_] = If[Prime[n] - 2 == 0, 6, Prime[n]*(Prime[n]^2 - 1)/2] a = Table[f[n], {n, 1, 25}] 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 CROSSREFS Cf. A084920, A127918. Sequence in context: A033931 A228847 A093901 * A178957 A104362 A123900 Adjacent sequences:  A117759 A117760 A117761 * A117763 A117764 A117765 KEYWORD nonn,easy AUTHOR Roger L. Bagula, Apr 14 2006 EXTENSIONS More terms from Vincenzo Librandi, Sep 29 2015 STATUS approved

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