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A203071 Triangle read by antidiagonals: T[r+1,c] = T[r,c]+T[r,c+1], but only nonprime numbers may be used. 2
1, 8, 9, 4, 12, 21, 14, 18, 30, 51, 6, 20, 38, 68, 119, 10, 16, 36, 74, 142, 261, 22, 32, 48, 84, 158, 300, 561, 27, 49, 81, 129, 213, 371, 671, 1232, 15, 42, 91, 172, 301, 514, 885, 1556, 2788, 35, 50, 92, 183, 355, 656, 1170, 2055, 3611, 6399, 40, 75, 125, 217, 400, 755, 1411, 2581, 4636 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This sequence is the lexicographically earliest one satisfying the given constraint. It is built using the smallest possible choice for the next term [of the first row A203072] not leading to a contradiction.

Is this a permutation of the nonprimes?

LINKS

Lars Blomberg, Table of n, a(n) for n = 1..20100 (the first 200 antidiagonals)

EXAMPLE

row 1:  1    8    4     14     6      10    22    27   15 ... [A203072]

row 2:    9    12    18     20    16     32    49    42 ...

row 3:      21   30     38     36     48    81    91 ...

row 4:         51    68     74    84    129   172 ...

row 5:           119    142   158    213   301 ...

row 6:              261    300    371   514 ...

row 7:                 561    671    885 ...

row 8:                    1232    1556 ...

row 9:                        2788 ...

PROG

(PARI) list_by_antidiagonals(a)={my(u=[]); for(i=1, #a, u=concat(u, a[i]); forstep(j=i-1, 1, -1, u=concat(u, a[j]+=a[j+1]))); u}  /* requires the first line as input */

CROSSREFS

Sequence in context: A010532 A243267 A243268 * A091725 A029689 A201294

Adjacent sequences:  A203068 A203069 A203070 * A203072 A203073 A203074

KEYWORD

nonn,tabl

AUTHOR

Eric Angelini, Dec 28 2011

STATUS

approved

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Last modified March 25 13:24 EDT 2017. Contains 284079 sequences.