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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A304207 a(1)=17; for n>1, a(n) = (a(n-1)^2 - 1)/2 if n is even, a(n-1) + 1 if n is odd. 1
17, 144, 145, 10512, 10513, 55261584, 55261585, 1526921388356112, 1526921388356113, 1165744463109679828308252234384, 1165744463109679828308252234385, 679480076635437837059150531810555804350472205781672488164112, 679480076635437837059150531810555804350472205781672488164113 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

{17, 144, 145}, {145, 10512, 10513}, {10513, 55261584, 55261585}, ... are sides {a < b < c} of the right triangles, with hypotenuse c = b + 1.

LINKS

Eric Chen, Table of n, a(n) for n = 1..21

MATHEMATICA

nxt[{n_, a_}]:={n+1, If[OddQ[n], (a^2-1)/2, a+1]}; NestList[nxt, {1, 17}, 20][[All, 2]] (* Harvey P. Dale, Mar 27 2021 *)

PROG

a(n) = if(n==1, 17, if(n%2, a(n-1)+1, (a(n-1)^2 - 1)/2)) \\ Eric Chen, Jun 09 2018

CROSSREFS

Same basic form as A076601, A076602, A076603, and A076604.

Sequence in context: A142815 A222478 A228254 * A163038 A216422 A008417

Adjacent sequences:  A304204 A304205 A304206 * A304208 A304209 A304210

KEYWORD

nonn

AUTHOR

Benjamin Knight, May 08 2018

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 25 11:16 EDT 2021. Contains 348249 sequences. (Running on oeis4.)