This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A045950 Triangles in Star of David matchstick arrangement of side n. 1
 0, 10, 59, 177, 394, 740, 1245, 1939, 2852, 4014, 5455, 7205, 9294, 11752, 14609, 17895, 21640, 25874, 30627, 35929, 41810, 48300, 55429, 63227, 71724, 80950, 90935, 101709, 113302, 125744, 139065, 153295, 168464, 184602, 201739, 219905, 239130, 259444 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS This is 1/2 the sequence A299965 which counts both the 'standard' and the 'inverted' triangles. - John King, Apr 05 2019 LINKS Colin Barker, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1). FORMULA a(n) = n*(10*n^2+9*n+1)/2. a(n) = 4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4). - Colin Barker, Dec 02 2014 G.f.: x*(x^2+19*x+10) / (x-1)^4. - Colin Barker, Dec 02 2014 a(n) = A299965(n)/2. - John King, Apr 05 2019 PROG (PARI) concat(0, Vec(x*(x^2+19*x+10)/(x-1)^4 + O(x^100))) \\ Colin Barker, Dec 02 2014 CROSSREFS Sequence in context: A044148 A044529 A129330 * A226796 A061001 A055586 Adjacent sequences:  A045947 A045948 A045949 * A045951 A045952 A045953 KEYWORD nonn,easy 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 October 17 11:57 EDT 2019. Contains 328108 sequences. (Running on oeis4.)