A065898 Which composite number is the product of first n primes (the n-th primorial number)?

0, 2, 19, 163, 1966, 26781, 468178, 9053660, 210809338, 6169323433, 192531847119, 7161249384065

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Example

a[3] = 19 because 2*3*5 = 30 is the 19th composite number: 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30.

Mathematica

Table[q = Product[ Prime[i], {i, 1, n}]; q - PrimePi[q] - 1, {n, 1, 12}]

Crossrefs

Cf. A002808, A000720, A002110.

Sequence in context: A037643 A198312 A057858 * A290188 A083196 A037526

Adjacent sequences: A065895 A065896 A065897 * A065899 A065900 A065901

Keyword

nonn

Author

Labos Elemer, Nov 28 2001

Extensions

More terms from Robert G. Wilson v, Nov 29 2001

Status

approved