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A105582 Smallest composite number n such that every divisor > 1 includes n as a substring. 0
10201, 121, 254, 39, 1849, 25, 16043, 497, 6889, 1691, 10201, 111221, 16129, 13169, 214411, 1532801, 516221, 117589, 1401847, 19361, 2520899, 44521, 512231, 235129, 582497, 628253, 726031, 395279, 802817, 295639, 921307, 31961, 4320991, 143323 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

All entries so far are semiprimes (A001358), some are perfect powers (A001597). - Robert G. Wilson v, May 09 2005

LINKS

Table of n, a(n) for n=0..33.

MATHEMATICA

fQ[n_, i_] := Block[{d = ToString /@ Drop[ Divisors[n], 1]}, Union[ StringPosition[d, ToString[i]]][[1]] != {}]; Do[k = 2; While[ PrimeQ[k] || fQ[k, n] == False, k++ ]; Print[k], {n, 0, 31}] (* Robert G. Wilson v, May 09 2005 *)

CROSSREFS

Sequence in context: A216262 A243410 A221119 * A243819 A258890 A255872

Adjacent sequences:  A105579 A105580 A105581 * A105583 A105584 A105585

KEYWORD

nonn,base

AUTHOR

David W. Wilson, May 08 2005

EXTENSIONS

More terms from Robert G. Wilson v, May 09 2005

STATUS

approved

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Last modified July 22 10:03 EDT 2019. Contains 325219 sequences. (Running on oeis4.)