A292426 Largest number k < primorial(n) such that omega(k) = n-1.

1, 5, 28, 204, 2280, 29946, 509124, 9694230, 223002780, 6468882420, 200545084740, 7420616447790, 304248924969990, 13082703773709570, 614888499146952030, 32589068024408996100, 1922759477457292844370, 117288363265448148804030, 7858320716113653603327510

Offset

1,2

Links

Table of n, a(n) for n=1..19.

Prog

(PARI) a(n) = b=prod(i=1, n, prime(i)); k={my(k=1); while(omega(b-k)<(n-1), k++); k; }; b-k
(PARI) a(n) = if(n==1, return(1)); my(A=vecprod(primes(n-1)), B=vecprod(primes(n))-1); (f(m, p, j) = my(r=0); forprime(q=p, sqrtnint(B\m, j), my(v=m*q); while(v <= B, if(j==1, if(v>=A && v > r, r = v), if(v*(q+1) <= B, r = max(r, f(v, q+1, j-1)))); v *= q)); r); f(1, 2, n-1); \\ Daniel Suteu, Sep 22 2023

Crossrefs

Cf. A001221, A002110.

Sequence in context: A151500 A356409 A332711 * A347005 A356025 A367272

Adjacent sequences: A292423 A292424 A292425 * A292427 A292428 A292429

Keyword

nonn

Author

Gionata Neri, Sep 29 2017

Extensions

a(12)-a(19) from Daniel Suteu, Sep 22 2023

Status

approved