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 A213019 Largest n-digit right-truncatable semiprime. 2

%I

%S 9,95,959,9599,95999,959999,9599999,95999987,959999879,9599998799,

%T 95999987999,959999879999,9599998791827,95999987918279,

%U 959999879182793,9599998791715333,95999987917153339,959999879171533399,9599998791715333999,95999987917153339993

%N Largest n-digit right-truncatable semiprime.

%C For the definition of a right-truncatable semiprime, see A213017. The largest possible right-truncatable semiprime a(38) = A085733(56076) = 95861957783594714393831931415189937897, found by S.S. Gupta, is the last term of this sequence.

%H Hugo Pfoertner, <a href="/A213019/b213019.txt">Table of n, a(n) for n = 1..38</a> (all terms)

%H Shyam Sunder Gupta, <a href="http://primes.utm.edu/curios/page.php?curio_id=6861">The largest right-truncatable semiprime</a>, Prime Curios.

%e a(1) = 9 = 3*3

%e a(2) = 95 = 5*19 and none of 96, 97, 98, 99 semiprime

%e a(3) = 959 = 7*137

%e a(4) = 9599 = 29*331

%e a(5) = 95999 = 17*5647

%e a(6) = 959999 = 643*1493

%e a(7) = 9599999 = 1019*9421

%e a(8) = 95999987 = 7349*13063, 9599998 = 2*4799999 and none of 95999988 ... 95999999 semiprime

%Y Cf. A001358, A085733, A213017, A213018.

%K nonn,base,fini,full

%O 1,1

%A _Hugo Pfoertner_, Jun 27 2012

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Last modified July 19 22:14 EDT 2019. Contains 325168 sequences. (Running on oeis4.)