

A277558


A variation on Recamán's sequence (A005132): to get a(n), we first try to subtract n from a(n1): a(n) = a(n1)n if positive and not already in the sequence; if not then a(n) = a(n1)+ni, where i >= 0 is the smallest number such that a(n1)+ni has not already appeared.


2



0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9, 24, 8, 25, 43, 62, 42, 63, 41, 18, 40, 15, 39, 66, 38, 67, 37, 68, 36, 69, 35, 70, 34, 71, 33, 72, 32, 73, 31, 74, 30, 75, 29, 76, 28, 77, 27, 78, 26, 79, 133, 188, 132, 189, 131, 190, 130, 191, 129, 192
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OFFSET

0,3


COMMENTS

Is it ever impossible to extend the sequence  meaning there is no number less than a(n1)+n which has not appeared?
After 10^11 terms, the smallest number which has not appeared is 609790506.


LINKS

Benjamin Chaffin, Table of n, a(n) for n = 0..10000


EXAMPLE

a(23) = 18. To get a(24) we try 1824, but that is negative; so we try 18+24 = 42, but 42 has already appeared; so we try 18+241, but 41 has also already appeared; so we try 18+242. 40 is positive and has not yet appeared, and so a(24) = 40.


CROSSREFS

Cf. A005132, A064387 (chooses a(n1)+n+i instead of a(n1)+ni).
Sequence in context: A074170 A076543 A274648 * A005132 A064388 A064387
Adjacent sequences: A277555 A277556 A277557 * A277559 A277560 A277561


KEYWORD

nonn


AUTHOR

Benjamin Chaffin, Oct 19 2016


STATUS

approved



