A078217 - OEIS

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A078217

Smallest multiple of n that begins with the concatenation of the positive integers <= n and coprime to n (in increasing order).

1, 10, 12, 132, 12340, 150, 1234562, 13576, 124578, 13790, 123456789104, 157116, 12345678910111209, 135911132, 124781113140, 135791113152, 123456789101112131415167, 1571113170, 1234567891011121314151617186

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

EXAMPLE

The positive integers <= n and coprime to 5 are 1, 2, 3 and 4, their concatenation is 1234; 12340 = 2468*5 is the smallest multiple of 5 that begins with 1234, so a(5) = 12340.

PROG

(PARI) {for(n=1, 19, k=floor(log(n)/log(10))+1; v=Str(); for(i=1, n, if(gcd(n, i)==1, 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; while(b>0, q=floor(s/n); while(b>0&&(p=q*n)<t, if(p>=s, print1(p, ", "); b=0, q++)); s=10*s; t=10*t))}

CROSSREFS

Cf. A078811.

Sequence in context: A119225 A155005 A219213 * A359356 A178639 A087392

Adjacent sequences: A078214 A078215 A078216 * A078218 A078219 A078220

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 22 2002

EXTENSIONS

Edited, corrected and extended by Klaus Brockhaus, Dec 06 2002

STATUS

approved