This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A096129 Middle term of a triple of consecutive numbers which are sums of two squares. 0
 1, 9, 73, 289, 801, 1801, 3529, 6273, 10369, 16201, 24201, 34849, 48673, 66249, 88201, 115201, 147969, 187273, 233929, 288801, 352801, 426889, 512073, 609409, 720001, 845001, 985609, 1143073, 1318689, 1513801, 1729801, 1968129, 2230273 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1). FORMULA a(n)=8*A000537(n) + 1. a(n)=1+2*n^2+4*n^3+2*n^4. G.f.: -(x^4+4*x^3+38*x^2+4*x+1)/(x-1)^5. [Colin Barker, Jul 28 2012] EXAMPLE 1801 is in the sequence because we may for instance write 1800 = 6^2 + 42^2; 1801 = 24^2 + 35^2; 1802 = 29^2 + 31^2. MATHEMATICA LinearRecurrence[{5, -10, 10, -5, 1}, {1, 9, 73, 289, 801}, 40] (* Harvey P. Dale, Oct 22 2019 *) CROSSREFS Cf. A001481. Sequence in context: A043079 A099973 A091986 * A291700 A143571 A244202 Adjacent sequences:  A096126 A096127 A096128 * A096130 A096131 A096132 KEYWORD nonn,easy AUTHOR Lekraj Beedassy, Jul 23 2004 EXTENSIONS Corrected and extended by Ray Chandler, Jul 29 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 December 15 20:00 EST 2019. Contains 330000 sequences. (Running on oeis4.)