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A133182
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A fractal sequence. Underline the first occurrence of "1", then the first occurrence of "2", the first "3", etc. The non underlined terms are the sequence itself.
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1
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1, 2, 1, 2, 3, 4, 5, 1, 2, 6, 3, 4, 7, 8, 5, 9, 1, 2, 10, 6, 3, 4, 11, 7, 8, 5, 12, 13, 9, 1, 2, 14, 10, 6, 3, 4, 15, 16, 17, 11, 7, 8, 5, 18, 19, 20, 12, 13, 9, 1, 2, 21, 22, 23, 14, 24, 10, 6, 3, 4, 25, 26, 15, 27, 16, 28, 17, 11, 7, 8, 5, 29, 18, 30, 19, 20, 12, 13, 9, 1, 2, 31, 21, 22, 32
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| For all [a,b,c] triplets of consecutive terms where (a+b) is prime, do underline c. The non underlined terms are the sequence itself.
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LINKS
| M. F. Hasler, Table of n, a(n) for n = 1..14868.
Eric Angelini, A fractal sequence with prime sums
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PROG
| (PARI) A133182(find=2007, show=1, a=[1, 2], no=0, ni=2)={ while(a[ #a]!=find, a=concat(a, if(isprime(a[ #a]+a[ #a-1]), no++, a[ni++ ]))); if(show, a, #a)} /* use A133182(N) to get all terms up to first occurrence of N ; A133182(N, 0) to get only the index of that term */ - M. F. Hasler (maximilian.hasler(AT)gmail.com), Oct 17, 2007
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CROSSREFS
| Sequence in context: A035534 A082854 A086742 * A071488 A114733 A167516
Adjacent sequences: A133179 A133180 A133181 * A133183 A133184 A133185
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KEYWORD
| nonn
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AUTHOR
| Eric Angelini (eric.angelini(AT)kntv.be), Oct 11 2007
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