A379535 a(n) is the least number that has n prime factors, counted by multiplicity, and n runs in its decimal representation.
2, 10, 102, 1012, 10104, 101010, 1010124, 10101216, 101010176, 1010101504, 10101010304, 101010101248, 1010101013280, 10101010101248, 101010101013504, 1010101010137856, 10101010101010432, 101010101010145280, 1010101010101010432, 10101010101010497536, 101010101010101084160, 1010101010101010620416, 10101010101010105368576
Offset: 1
Examples
a(4) = 1012 because 1012 = 2^2 * 11 * 23 has 4 prime factors, counted with multiplicity, and 4 runs in its decimal representation, and no smaller number works.
Programs
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Maple
f:= proc(n) local x,x0,L,t,i; if n::odd then x0:= (10^(n+1)-1)/99 else x0:= (10^(n+1)-10)/99 fi; for x from x0 do L:= convert(x,base,10); t:= nops(L) - numboccur(0, L[2..-1]-L[1..-2]); if t = n and numtheory:-bigomega(x) = n then return x fi od end proc: map(f, [$1..23]);
Comments