Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #10 Feb 23 2015 23:09:43
%S 4,6,8,9,14,16,18,24,26,28,34,36,38,39,44,46,48,49,54,56,58,64,66,68,
%T 69,74,76,78,84,86,88,94,96,98,99,104,106,108,114,116,118,124,126,128,
%U 134,136,138,144,146,148,154,156,158,164,166,168
%N Left-truncatable composites: every decimal suffix is a composite number.
%H Stanislav Sykora, <a href="/A254755/b254755.txt">Table of n, a(n) for n = 1..10000</a>
%e 549 is a member because 549, 49, and 9 are all composites.
%o (PARI) isComposite(n) = (n>2)&&(!isprime(n));
%o 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);}
%Y Cf. A103443 (left-truncatable primes), A202260 (right-truncatable composites), A254750.
%K nonn,base
%O 1,1
%A _Stanislav Sykora_, Feb 15 2015