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A278492 Square array where row n (n >= 0) gives the numbers remaining after the n-th round of the Flavius sieve, read by descending antidiagonals. 5
1, 2, 1, 3, 3, 1, 4, 5, 3, 1, 5, 7, 7, 3, 1, 6, 9, 9, 7, 3, 1, 7, 11, 13, 13, 7, 3, 1, 8, 13, 15, 15, 13, 7, 3, 1, 9, 15, 19, 19, 19, 13, 7, 3, 1, 10, 17, 21, 25, 25, 19, 13, 7, 3, 1, 11, 19, 25, 27, 27, 27, 19, 13, 7, 3, 1, 12, 21, 27, 31, 31, 31, 27, 19, 13, 7, 3, 1, 13, 23, 31, 37, 39, 39, 39, 27, 19, 13, 7, 3, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
The terms of square array A(row,col) are read by descending antidiagonals as A(0,0), A(0,1), A(1,0), A(0,2), A(1,1), A(2,0), ...
LINKS
D. Wilson et al., Interesting sequence, SeqFan list, Nov. 2016
FORMULA
A(n,k) = 1 + A278482(n,k).
EXAMPLE
The top left corner of the array:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10 (row 0: start from A000027)
1, 3, 5, 7, 9, 11, 13, 15, 17, 19 (after the 1st round, A005408 remain)
1, 3, 7, 9, 13, 15, 19, 21, 25, 27 (after the 2nd, A047241)
1, 3, 7, 13, 15, 19, 25, 27, 31, 37
1, 3, 7, 13, 19, 25, 27, 31, 39, 43
1, 3, 7, 13, 19, 27, 31, 39, 43, 49
1, 3, 7, 13, 19, 27, 39, 43, 49, 61
1, 3, 7, 13, 19, 27, 39, 49, 61, 63
1, 3, 7, 13, 19, 27, 39, 49, 63, 67
1, 3, 7, 13, 19, 27, 39, 49, 63, 79
PROG
(Scheme)
(define (A278492 n) (A278492bi (A002262 n) (A025581 n)))
(define (A278492bi row col) (+ 1 (A278482bi row col)))
CROSSREFS
One more than A278482.
Transpose: A278493.
Main diagonal: A000960.
Cf. A278507 (the numbers removed at each round).
Similarly constructed arrays for other sieves: A258207, A260717.
Sequence in context: A188002 A186974 A286312 * A128139 A208721 A208777
KEYWORD
nonn,tabl
AUTHOR
Antti Karttunen, Nov 23 2016, after David W. Wilson's posting on SeqFan-list Nov 22 2016
STATUS
approved

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Last modified March 28 16:58 EDT 2024. Contains 371254 sequences. (Running on oeis4.)