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 A287515 a(n) = position of n-th 0 when sequence is written in base 2. 1
 2, 7, 8, 9, 11, 12, 15, 20, 21, 27, 29, 30, 32, 34, 38, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 62, 64, 65, 68, 70, 73, 74, 77, 78, 80, 83, 85, 86, 89, 91, 95, 98, 101, 108, 109, 110, 114, 116, 120, 127, 128, 134, 136, 137, 138, 139, 140, 141, 143, 144, 145, 146, 147, 150, 151, 152, 154, 155, 157, 158, 159, 162 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A167500 lists the positions of 1's when the sequence is written in binary. This sequence lists the positions of 0's. When written in binary, it begins 10, 111, 1000, 1001, 1011... The first 0 appears at position 2, so a(1) = 2 = 10. The second 0 appears at position 7, so a(2) = 7 = 111. The third 0 appears at position 8, so a(3) = 8 = 1000. The sequence then becomes self-generating, because entries are added to it faster than 0's are detected in it. LINKS Anthony Sand, Table of n, a(n) for n = 1..10000 FORMULA a(n) = zeropos([sequence],n). EXAMPLE a(1) = zeropos([10...],1) = 2, a(2) = zeropos([10,111,1000...],2) = 7, a(3) = zeropos([10,111,1000...],3) = 8, a(4) = zeropos([10,111,1000...],4) = 9, a(5) = zeropos([10,111,1000,1001...],5) = 11. PROG (PARI) { zeroposseq()= smx=100; s=vector(smx); s[1]=2; s[2]=7; s[3]=8; si=0; dig=digits(s[1], 2); di=1; i=1; dl=0; while(si#dig, di++; dig=digits(s[di], 2); i=1; ); ); } CROSSREFS Cf. A167500, A167502. Sequence in context: A064517 A270804 A167457 * A260581 A179772 A047354 Adjacent sequences:  A287512 A287513 A287514 * A287516 A287517 A287518 KEYWORD nonn,base,easy AUTHOR Anthony Sand, May 26 2017 STATUS approved

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Last modified September 21 12:33 EDT 2020. Contains 337272 sequences. (Running on oeis4.)