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A299975
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Lexicographic first sequence of positive integers such that a(n) + a(n+1) has a digit 5, and no term occurs twice.
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1
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1, 4, 11, 14, 21, 24, 26, 9, 6, 19, 16, 29, 22, 3, 2, 13, 12, 23, 27, 8, 7, 18, 17, 28, 25, 10, 5, 20, 15, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 76, 39, 36, 49, 46, 59, 56, 69, 66, 79, 71, 34, 31, 44, 41, 54, 51, 64, 61, 74, 77, 38, 37, 48, 47, 58, 57, 68, 67, 78, 72, 33, 32, 43, 42, 53, 52, 63, 62, 73, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125
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OFFSET
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1,2
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COMMENTS
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A permutation of the positive integers.
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LINKS
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PROG
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(PARI) a(n, f=1, d=5, a=1, u=[a])={for(n=2, n, f&&if(f==1, print1(a", "), write(f, n-1, " "a)); for(k=u[1]+1, oo, setsearch(u, k)&&next; setsearch(Set(digits(a+k)), d)&&(a=k)&&break); u=setunion(u, [a]); u[2]==u[1]+1&&u=u[^1]); a}
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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