A060019 a(n) = floor(2*sqrt(prime(n)-2)) where prime(n) = n-th prime.

0, 2, 3, 4, 6, 6, 7, 8, 9, 10, 10, 11, 12, 12, 13, 14, 15, 15, 16, 16, 16, 17, 18, 18, 19, 19, 20, 20, 20, 21, 22, 22, 23, 23, 24, 24, 24, 25, 25, 26, 26, 26, 27, 27, 27, 28, 28, 29, 30, 30, 30, 30, 30, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 35, 35, 35

Offset

1,2

Links

Table of n, a(n) for n=1..66.

J. R. Griggs, Spanning subset sums for finite Abelian groups, Discrete Math., 229 (2001), 89-99.

Formula

For n=1, prime(1) is 2, and a(n) = 0.

Prog

(PARI) a(n) = floor(2*sqrt(prime(n)-2)); \\ Michel Marcus, Nov 26 2015
(PARI) a(n, p=prime(n))=sqrtint(4*p-8) \\ Charles R Greathouse IV, Jan 24 2018

Crossrefs

Cf. A060018.

Sequence in context: A154257 A336406 A297351 * A359100 A093451 A106006

Adjacent sequences: A060016 A060017 A060018 * A060020 A060021 A060022

Keyword

nonn

Author

N. J. A. Sloane, Mar 17 2001

Extensions

Offset set to 1 by Michel Marcus, Nov 26 2015

Status

approved