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!)
A087092 Descending squares: which squares can be packed with at least 2 squares so that every square directly above a square is strictly smaller? It is conjectured that the answer is all except those in this sequence. 0
1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 15, 17, 19, 23, 33 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..15.

E. Friedman, Illustrations

EXAMPLE

6, 10 and 25 are not in the sequence: To pack a 6 X 6 square, use 2 3 X 3s on the bottom, 3 2 X 2's above that and 6 1 X 1's on the top. For 10 X 10, use 2 5 X 5s on the bottom, a 4 X 4 and 2 3 X 3s above that; put 4 1 X 1's above the 4 X 4 and 3 2 X 2's above the 3 X 3s. For 25 X 25, use a 15 X 15 and a 10 X 10 on the bottom and 2 5 X 5s above the 10 X 10; above that use a 7 X 7, a 6 X 6 and 3 4 X 4s; the rest can be packed with 3 X 3s, 2 X 2's and 1 X 1's.

CROSSREFS

Sequence in context: A321698 A325394 A062491 * A046684 A082377 A166401

Adjacent sequences:  A087089 A087090 A087091 * A087093 A087094 A087095

KEYWORD

nonn,fini,full

AUTHOR

Erich Friedman, Oct 19 2003

EXTENSIONS

Edited by Dean Hickerson, Oct 24 2003

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 September 16 15:58 EDT 2021. Contains 347473 sequences. (Running on oeis4.)