A178431 Joint-rank array of the sums of two primes.

1, 2, 2, 4, 3, 4, 6, 5, 5, 6, 9, 7, 7, 7, 9, 11, 10, 8, 8, 10, 11, 14, 12, 12, 10, 12, 12, 14, 16, 15, 13, 13, 13, 13, 15, 16, 19, 17, 17, 15, 17, 15, 17, 17, 19, 23, 20, 18, 18, 18, 18, 18, 18, 20, 23, 25, 24, 21, 20, 21, 20, 21, 20, 21, 24, 25

Offset

1,2

Comments

Joint-rank arrays are defined at A157927 for arrays in which duplicates occur (and otherwise, at A182801).

Links

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

Example

A corner of the array A178400 of sums of two primes:
4...5...7...9..13...
5...6...8..10..14...
7...8..10..12..14...
9..10..12..14..18...
Each of these P(i,j) is replaced by its rank when all the
numbers P(h,k) are jointly ranked, leaving A178431:
1...2...4...6...9...
2...3...5...7..10...
4...5...7...8..12...
6...7...8..10..13...
The number of distinct sums p+q <=13 is 9.

Crossrefs

Cf. A014092, A157927, A178400.

Sequence in context: A079707 A233511 A205793 * A233574 A353925 A157927

Adjacent sequences: A178428 A178429 A178430 * A178432 A178433 A178434

Keyword

nonn,tabl

Author

Clark Kimberling, Dec 21 2010

Status

approved