This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A245647 The middle member 'b' of the Pythagorean triples (a,b,c) ordered by increasing c, where the triples consist of a triangular number, a square number and a pentagonal number. 2
 4, 12, 105, 2625 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Next term comes from a triple with c > 10^5. LINKS EXAMPLE a(1) = 4 as the first such Pythagorean triple is (3,4,5). The next three triples are (9,12,15), (100,105,145), (900,2625,2775). MATHEMATICA n=10^3; ppt={}; list={}; pos=1; t[x_]:=(IntegerPart[Sqrt[2*x]])*(IntegerPart[Sqrt[2*x]]+1)/2; ls[x_]:=Length[Sqrt[x]]; lis[x_]:=Length[IntegerPart[Sqrt[x]]]; lp[x_]:=Length[(Sqrt[24*x+1]+1)/6]; lip[x_]:=Length[IntegerPart[(Sqrt[24*x+1]+1)/6]]; Do[y=x+1; z=y+1; While[z<=n, While[z^2

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 14 11:44 EDT 2019. Contains 327996 sequences. (Running on oeis4.)