A078296 a(1) = 1, a(n) for n > 1 is the smallest multiple of a(n-1) that begins with the concatenation 123... up to n.

1, 12, 1236, 1234764, 12345170472, 1234566427881888, 1234567662448315881888, 123456781059643537568590582656, 12345678970161821174363821245734078592, 123456789109025621175870796087877366124764227584

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Example

For n = 3 we have a(n-1) = a(2) = 12; 103*12 = 1236 is the smallest multiple of a(2) that begins with 123, so a(3) = 1236.

Prog

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

Crossrefs

Cf. A078395, A078396, A078397.

Sequence in context: A078294 A317953 A009155 * A239164 A209176 A351630

Adjacent sequences: A078293 A078294 A078295 * A078297 A078298 A078299

Keyword

base,nonn

Author

Amarnath Murthy, Nov 26 2002

Extensions

Edited and extended by Klaus Brockhaus, Dec 06 2002

Status

approved