A073819 a(n) = prime(i) such that prime(i)*(n+1-i) is maximized (1 <= i <= n).

2, 2, 2, 5, 5, 11, 11, 11, 11, 17, 17, 17, 17, 29, 29, 29, 29, 29, 37, 37, 37, 41, 41, 41, 41, 59, 59, 59, 59, 59, 59, 59, 67, 67, 67, 71, 71, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 97, 127, 127, 127, 127, 127, 127, 127, 127, 149, 149, 149, 149, 149, 149, 149, 149

Offset: 1

Author

David Wasserman, Aug 13 2002

Keywords

• easy
• nonn

Comments

3 is the only n for which the maximum is not unique; a(3) could also be given as 3.

Examples

			For n = 5, we take the first 5 primes in ascending order and multiply them by the numbers from 5 to 1 in descending order: 2*5 = 10 3*4 = 12 5*3 = 15 7*2 = 14 11*1 = 11 The largest product is 15, so a(5) = 5.
		

Crossrefs

Cf. A073818, A073820.

Formula

a(n) = A073818(n)/A073820(n).