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Search: id:A065075
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| A065075 |
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Sum of digits of the sum of the preceding numbers. |
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+0
13
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| 1, 1, 2, 4, 8, 7, 5, 10, 11, 13, 8, 7, 14, 10, 2, 4, 8, 7, 5, 10, 11, 13, 8, 16, 14, 19, 11, 13, 8, 7, 14, 10, 11, 13, 8, 7, 5, 10, 11, 13, 17, 16, 14, 10, 11, 13, 8, 16, 14, 19, 20, 13, 8, 16, 14, 19, 20, 13, 8, 16, 14, 19, 20, 22, 17, 16, 14, 19, 20, 13, 17, 16, 14, 19, 20, 13
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Same digital roots as A004297 (a(1) = 1, a(n) = sum of digits of all previous terms) and A001370 (Sum of digits of 2^n)); they end in the cycle {1 2 4 8 7 5}. - Alexandre Wajnberg (alexandre.wajnberg(AT)skynet.be), Dec 11 2005
The missing numbers are precisely the multiples of 3. - Alexandre Wajnberg (alexandre.wajnberg(AT)skynet.be), Dec 28 2005
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FORMULA
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a(1) = 1, a(2) = 1, a(n) = sum of digits of (a(1)+a(2)+...+a(n-1)).
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EXAMPLE
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a(6) = 7 because a(1)+a(2)+a(3)+a(4)+a(5) = 16 and 7 = 1+6
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PROGRAM
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(PARI): digitsum(n) = local(v, d); v=[]; while(n>0, d=divrem(n, 10); n=d[1]; v=concat(v, d[2])); sum(j=1, matsize(v)[2], v[j]) a065075(m) = local(a, j, s); a=1; print1(a, ", "); s=a; for(j=1, m, a=digitsum(s); print1(a, ", "); s=s+a) a065075(80)
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CROSSREFS
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Sequence in context: A071571 A029898 A021406 this_sequence A001370 A039794 A113417
Adjacent sequences: A065072 A065073 A065074 this_sequence A065076 A065077 A065078
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KEYWORD
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nonn,base,easy
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AUTHOR
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Bodo Zinser (BodoZinser(AT)Compuserve.com), Nov 09 2001
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EXTENSIONS
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More terms from Larry Reeves (larryr(AT)acm.org) and Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Nov 13 2001
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