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Search: id:A071980
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| A071980 |
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If n = abcd (say) in decimal, then a(n) = a + ab + abc + abcd + bcd + cd + d. |
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+0
2
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| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 77, 79
(list; graph; listen)
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OFFSET
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0,3
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EXAMPLE
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a(1347) = 1 + 13 + 134 1347 + 347 + 47 + 7 = 1896.
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MATHEMATICA
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f[n_] := Block[{lead = trail = IntegerDigits[n], l = Floor[Log[10, n] + 1], s = -n}, While[l > 0, s = s + FromDigits[lead] + FromDigits[trail]; lead = Drop[lead, -1]; trail = Drop[trail, 1]; l-- ]; s]; Table[ f[n], {n, 0, 80}]
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PROGRAM
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(PARI) a(n)=local(l); if(n<1, 0, l=1+log(n)\log(10); sum(i=1, l-1, n\10^i+n%(10^i), n))
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CROSSREFS
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Sequence in context: A032959 A061383 A059708 this_sequence A058183 A080676 A033061
Adjacent sequences: A071977 A071978 A071979 this_sequence A071981 A071982 A071983
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jun 18 2002
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EXTENSIONS
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Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 23 2002
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