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A254755 Left-truncatable composites: every decimal suffix is a composite number. 6
4, 6, 8, 9, 14, 16, 18, 24, 26, 28, 34, 36, 38, 39, 44, 46, 48, 49, 54, 56, 58, 64, 66, 68, 69, 74, 76, 78, 84, 86, 88, 94, 96, 98, 99, 104, 106, 108, 114, 116, 118, 124, 126, 128, 134, 136, 138, 144, 146, 148, 154, 156, 158, 164, 166, 168 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Stanislav Sykora, Table of n, a(n) for n = 1..10000

EXAMPLE

549 is a member because 549, 49, and 9 are all composites.

PROG

(PARI) isComposite(n) = (n>2)&&(!isprime(n));

isLeftTruncatableComposite(n, b=10) = {my(k=b); if(!isComposite(n), return(0); ); while(n\k>0, if(!isComposite(n%k), return(0); ); k*=b); return(1); }

CROSSREFS

Cf. A103443 (left-truncatable primes), A202260 (right-truncatable composites), A254750.

Sequence in context: A285586 A118951 A262389 * A275624 A228019 A228020

Adjacent sequences:  A254752 A254753 A254754 * A254756 A254757 A254758

KEYWORD

nonn,base

AUTHOR

Stanislav Sykora, Feb 15 2015

STATUS

approved

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Last modified August 22 12:56 EDT 2017. Contains 290948 sequences.