The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A100156 Structured truncated tetrahedral numbers. 3
 1, 12, 44, 108, 215, 376, 602, 904, 1293, 1780, 2376, 3092, 3939, 4928, 6070, 7376, 8857, 10524, 12388, 14460, 16751, 19272, 22034, 25048, 28325, 31876, 35712, 39844, 44283, 49040, 54126, 59552 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..5000 Index entries for linear recurrences with constant coefficients, signature (4, -6, 4, -1). FORMULA a(n) = (1/6)*(11*n^3 - 3*n^2 - 2*n). From Harvey P. Dale, Sep 28 2011: (Start) a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4); a(0)=1, a(1)=12, a(2)=44, a(3)=108. G.f.: x*(2*x*(x+4)+1)/(x-1)^4. (End) E.g.f.: x*(6 + 30*x + 11*x^2)*exp(x)/6. - G. C. Greubel, Oct 18 2018 MATHEMATICA Table[(11n^3-3n^2-2n)/6, {n, 40}] (* or *) LinearRecurrence[{4, -6, 4, -1}, {1, 12, 44, 108}, 40] (* Harvey P. Dale, Sep 28 2011 *) PROG (MAGMA) [(1/6)*(11*n^3-3*n^2-2*n): n in [1..40]]; // Vincenzo Librandi, Jul 19 2011 (PARI) vector(50, n, (11*n^3 - 3*n^2 - 2*n)/6) \\ G. C. Greubel, Oct 18 2018 CROSSREFS Cf. A100155, A100157 for adjacent structured Archimedean solids; A100145 for more on structured polyhedral numbers. Similar to truncated tetrahedral numbers A005906. Sequence in context: A106808 A296181 A007899 * A320998 A294521 A309817 Adjacent sequences:  A100153 A100154 A100155 * A100157 A100158 A100159 KEYWORD easy,nonn AUTHOR James A. Record (james.record(AT)gmail.com), Nov 07 2004 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
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 26 15:30 EST 2020. Contains 338640 sequences. (Running on oeis4.)