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A178431 Joint-rank array of the sums of two primes. 2
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 (list; table; graph; refs; listen; history; text; internal format)
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 A157927 A227256

Adjacent sequences:  A178428 A178429 A178430 * A178432 A178433 A178434

KEYWORD

nonn,tabl

AUTHOR

Clark Kimberling, Dec 21 2010

STATUS

approved

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Last modified September 25 18:51 EDT 2021. Contains 347659 sequences. (Running on oeis4.)