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!)
 A115288 a(n) is the smallest number representable in exactly n ways as a sum of 2 triangular numbers and one square (each of them >= 0). 4
 0, 1, 4, 7, 10, 16, 22, 25, 64, 46, 70, 67, 92, 85, 160, 115, 106, 136, 200, 157, 190, 172, 256, 235, 568, 277, 370, 337, 400, 367, 340, 550, 556, 442, 1102, 445, 472, 631, 610, 535, 682, 697, 652, 1075, 956, 850, 1984, 865, 1172, 997, 862, 1081, 1462, 1135, 1060 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE a(4)=7 since 7 can be expressed in 4 ways, 7= T(3)+T(1)+0^2 = T(3)+T(0)+1^2 = T(2)+T(0)+2^2 = T(2)+T(2)+1^2 and none of the numbers from 0 to 6 can be expressed in 4 ways. MATHEMATICA V=Table[0, {i, 2500}]; T[n]:=n(n+1)/2; Do[a=T[i]+T[j]+k^2; If[a<2500, V[[a+1]]++ ], {i, 0, 71}, {j, 0, i}, {k, 0, 50}]; Table[Position[V, z][[1, 1]]-1, {z, 60}] CROSSREFS Cf. A115289, A000437, A061262. Sequence in context: A177965 A179209 A168565 * A180080 A153003 A213484 Adjacent sequences:  A115285 A115286 A115287 * A115289 A115290 A115291 KEYWORD nonn AUTHOR Giovanni Resta, Jan 19 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 | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.