A090958 - OEIS

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A090958

Numbers in increasing order such that the least multiple of prime(n) in the sequence is primorial(n).

1, 2, 4, 6, 8, 9, 12, 16, 18, 24, 27, 30, 32, 36, 40, 45, 48, 50, 54, 60, 64, 72, 75, 80, 81, 90, 96, 100, 108, 120, 125, 128, 135, 144, 150, 160, 162, 180, 192, 200, 210, 216, 224, 225, 240, 243, 245, 250, 252, 256, 270, 280, 288, 294, 300, 315, 320, 324, 336, 343

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

The sequence is obtained by including all those numbers between primorial(n) and primorial(n+1) which have the largest prime divisor < = prime(n).

LINKS

Matthieu Pluntz, Table of n, a(n) for n = 0..34184

MATHEMATICA

{{1}}~Join~Array[Function[{p, q}, Select[Range[p, p NextPrime[q] - 1], FactorInteger[#][[-1, 1]] <= q &]] @@ {Product[Prime@ i, {i, #}], Prime[#]} &, 4] // Flatten (* Michael De Vlieger, Nov 18 2017 *)

PROG

(PARI) v = vector(1000); pr = 1; forprime(p = 2, 1000, pr *= p; v[p] = pr); for (n = 2, 1000, f = factor(n); p = f[matsize(f)[1], 1]; if (n >= v[p], print(n))); \\ David Wasserman, Feb 22 2006

CROSSREFS

Cf. A090959.

Sequence in context: A146982 A352488 A298305 * A245047 A074901 A189294

Adjacent sequences: A090955 A090956 A090957 * A090959 A090960 A090961

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Dec 31 2003

EXTENSIONS

More terms from David Wasserman, Feb 22 2006

STATUS

approved