OFFSET
1,1
COMMENTS
a(1)=2 and a(2)=3 are the only terms greater than the n-th highly composite number.
Terms are powers of primes (A000961). - David A. Corneth, Jul 12 2020
LINKS
Matthew Doucette, Lowest Unused Anti-Prime (Highly Composite Number) Factors
Matthew Doucette, Highly Composite Numbers (Anti-Primes) (first missing number from factorizations)
Matthew Doucette, Calculating Highly Composite Numbers (Anti-Primes) (first missing number from factorizations)
EXAMPLE
a(1) = 2 = least non-divisor of 1.
a(2) = 3 = least non-divisor of 2.
a(3) = 3 = least non-divisor of 4.
a(4) = 4 = least non-divisor of 6.
a(5) = 5 = least non-divisor of 12.
...
PROG
(PARI) nondiv(n) = {for (k=1, n+1, if (n % k, return (k)); ); } \\ A007978
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
CROSSREFS
KEYWORD
nonn
AUTHOR
Matthew Doucette, Jun 05 2020
EXTENSIONS
a(67)-a(71) from David A. Corneth, Jul 12 2020
STATUS
approved