cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A379167 Table read by row, where T(n,k), n>0 and k>0, represents the smallest n-digit number that is the product of k distinct primes and is sandwiched between semiprime numbers, or -1 if no such number exists.

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%I A379167 #32 Jan 11 2025 16:26:43
%S A379167 5,-1,34,-1,122,186,870,-1,1042,1146,1190,5610,-1,10118,10002,10030,
%T A379167 10230,39270,-1,100462,100158,100030,100122,110670,881790,-1,1000478,
%U A379167 1000022,1000010,1000758,1001130,1009470,-1,10000202,10000258,10000002,10000218,10001670,10010910,15825810
%N A379167 Table read by row, where T(n,k), n>0 and k>0, represents the smallest n-digit number that is the product of k distinct primes and is sandwiched between semiprime numbers, or -1 if no such number exists.
%e A379167 Smallest n-digit numbers m product of k distinct primes sandwiched between two semiprimes m-1 and m+1:
%e A379167   n k    m-1,           m,               m+1
%e A379167   1 1   4 = 2^2,      5 = 5,            6 = 2 * 3;
%e A379167   2 2  33 = 3 * 11,  34 = 2 * 17,      35 = 5 * 7;
%e A379167   3 3 185 = 5 * 37, 186 = 2 * 3 * 31, 187 = 11 * 17;
%e A379167 Table read by rows:
%e A379167    5;
%e A379167   -1,       34;
%e A379167   -1,      122,      186,      870;
%e A379167   -1,     1042,     1146,     1190,     5610;
%e A379167   -1,    10118,    10002,    10030,    10230,    39270;
%e A379167   -1,   100462,   100158,   100030,   100122,   110670,   881790;
%e A379167   -1,  1000478,  1000022,  1000010,  1000758,  1001130,  1009470;
%e A379167   -1, 10000202, 10000258, 10000002, 10000218, 10001670, 10010910, 15825810;
%e A379167   ...
%Y A379167 Cf. A001358, A067885, A378627, A378097.
%K A379167 sign,tabf,base
%O A379167 1,1
%A A379167 _Jean-Marc Rebert_, Dec 17 2024