login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A153874 Numbers n = abc...k such that a^2*b^2*c^2*...k^2 - 1 = n. 0
143, 323, 11663 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..3.

EXAMPLE

1) 143 = 1^2 * 4^2 * 3^2 - 1 = 1 * 16* 9 - 1. 2) 323 = 3^2 * 2^2 * 3^2 - 1 = 9 * 4 * 9 - 1. 3) 1663 = 1^2 * 1^2* 6^2 * 6^2 * 3^2 - 1 = 1 * 1 * 36 * 36 * 9 - 1.

PROG

(PARI) n=1; while(n!=10^16, n+=1; j=n^2-1; k=1; while(j!=0, k=k*(j%10)^2; j=floor(j/10)); if(k-1==n^2-1, print(n^2-1)))

CROSSREFS

Sequence in context: A176876 A257767 A158136 * A003902 A261074 A213337

Adjacent sequences:  A153871 A153872 A153873 * A153875 A153876 A153877

KEYWORD

base,nonn,fini,full,bref

AUTHOR

Vikram Pandya, Jan 03 2009

EXTENSIONS

Edited by N. J. A. Sloane, Jan 03 2009

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.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 18 10:38 EST 2017. Contains 294887 sequences.