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%I #79 Aug 07 2020 19:27:08
%S 2,3,3,4,5,5,5,5,7,7,7,7,7,7,9,8,9,11,11,11,11,11,11,11,13,11,11,13,
%T 13,13,13,13,13,13,13,13,13,17,16,17,17,17,17,17,17,17,17,17,17,17,17,
%U 17,19,17,19,19,19,19,19,19,19,19,19,19,23,19,19,23,23,19,23
%N a(n) is the smallest positive integer that is not a divisor of the n-th highly composite number (A002182).
%C a(1)=2 and a(2)=3 are the only terms greater than the n-th highly composite number.
%C Terms are powers of primes (A000961). - _David A. Corneth_, Jul 12 2020
%H Matthew Doucette, <a href="http://xona.com/antiprimefactors/">Lowest Unused Anti-Prime (Highly Composite Number) Factors</a>
%H Matthew Doucette, <a href="http://xona.com/antiprimes/">Highly Composite Numbers (Anti-Primes)</a> (first missing number from factorizations)
%H Matthew Doucette, <a href="https://youtu.be/f7EKdzViIQ8">Calculating Highly Composite Numbers (Anti-Primes)</a> (first missing number from factorizations)
%F a(n) = A007978(A002182(n)).
%e a(1) = 2 = least non-divisor of 1.
%e a(2) = 3 = least non-divisor of 2.
%e a(3) = 3 = least non-divisor of 4.
%e a(4) = 4 = least non-divisor of 6.
%e a(5) = 5 = least non-divisor of 12.
%e ...
%o (PARI) nondiv(n) = {for (k=1, n+1, if (n % k, return (k)););} \\ A007978
%o lista(nn) = {my(list=List([1]), r=1); forstep(n=2, nn, 2, if(numdiv(n)>r, r=numdiv(n); listput(list, n));); apply(x->nondiv(x), Vec(list));} \\ _Michel Marcus_, Jun 10 2020
%Y Cf. A000961, A002182, A007978.
%K nonn
%O 1,1
%A _Matthew Doucette_, Jun 05 2020
%E a(67)-a(71) from _David A. Corneth_, Jul 12 2020
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