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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 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: A335963 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 February 5 18:15 EST 2023. Contains 360087 sequences. (Running on oeis4.)