login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A078215 a(1) = 1; a(n) for n > 1 is the smallest multiple of a(n-1) that is a square and begins with n. 3
1, 25, 3025, 48400, 5856400, 6377619600, 771691971600, 840372557072400, 915165714651843600, 1057931566137531201600, 1152087475523771478542400, 1254623260845387140132673600, 1366284731060626595604481550400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..13.

EXAMPLE

For n = 3 we have a(n-1) = a(2) = 25; 121*25 = 3025 is the smallest multiple of 25 that is a square and begins with 3, so a(3) = 3025.

PROG

(PARI) {print1(a=1, ", "); for(n=2, 13, k=floor(log(a)/log(10))+1; s=n; t=s+1; m=floor(log(s)/log(10))+1; d=k-m; s=s*10^d; t=t*10^d; b=1; while(b>0, q=floor(s/a); while(b>0&&(p=q*a)<t, if(p>=s&&issquare(p), print1(p, ", "); b=0, q++)); s=10*s; t=10*t); a=p)}

CROSSREFS

Cf. A078216, A078815.

Sequence in context: A209850 A014797 A077519 * A075414 A226277 A013737

Adjacent sequences:  A078212 A078213 A078214 * A078216 A078217 A078218

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 22 2002

EXTENSIONS

Edited and extended by Klaus Brockhaus, Dec 06 2002

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 January 27 15:45 EST 2022. Contains 350607 sequences. (Running on oeis4.)