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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A027568 Numbers that are both triangular and tetrahedral. 15
 0, 1, 10, 120, 1540, 7140 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 REFERENCES J.-M. De Koninck, Ces nombres qui nous fascinent, Ellipses (Paris), 2008 (entry 10, page 3; entry 120, page 41). L. J. Mordell, Diophantine Equations, Ac. Press, page 258. P. Odifreddi, Il museo dei numeri, Rizzoli, 2014, page 224. J. Roberts, The Lure of the Integers, page 53. LINKS E. T. Avanesov, Solution of a problem on figurate numbers (in Russian), Acta Arith. 12 1966/1967 pages 409-420. P. De Geest, Palindromic Tetrahedrals M. Gardner, Letter to N. J. A. Sloane, circa Aug 11 1980, concerning A001110, A027568, A039596, etc. J. Roberts, The Lure of the Integers, pp. 53. (Annotated scanned copy) Eric Weisstein's World of Mathematics, Tetrahedral Number MAPLE {seq(binomial(i, 3), i=0..100000) } intersect {seq(binomial(k, 2), k= 0..100000)}; # Zerinvary Lajos, Apr 26 2008 MATHEMATICA f3[n_]:=n*(n+1)*(n+2)/6; TriangularNumberQ[n_]:=Floor[Sqrt[2*n]]*(Floor[Sqrt[2*n]]+1)/2==n; Select[f3[Range[5! ]], TriangularNumberQ[ # ]&] (* Vladimir Joseph Stephan Orlovsky, Feb 16 2010 *) With[{trno=Accumulate[Range[0, 1000]]}, Intersection[trno, Accumulate[ trno]]] (* Harvey P. Dale, May 25 2014 *) PROG (PARI) for(n=0, 1e3, if(ispolygonal(t=n*(n+1)*(n+2)/6, 3), print1(t", "))) \\ Charles R Greathouse IV, Apr 07 2013 CROSSREFS Intersection of A000217 and A000292. Cf. A102349, A102461, A102772. Sequence in context: A182605 A024127 A005949 * A318495 A320760 A034255 Adjacent sequences:  A027565 A027566 A027567 * A027569 A027570 A027571 KEYWORD nonn,fini,full AUTHOR 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 February 20 07:41 EST 2020. Contains 332069 sequences. (Running on oeis4.)