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A053392 a(n) is the concatenation of the sums of every pair of consecutive digits of n (with a(n) = 0 for 0 <= n <= 9). 5
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 27, 28, 29, 210 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,12

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Erich Friedman, Problem of the Month (February 2000).

EXAMPLE

For n=10 we have 10 -> 1+0 = 1, hence a(10)=1;

987 -> 9+8.8+7 -> 17.15 -> 1715, so a(987)=1715.

MATHEMATICA

a[n_] := Total /@ Transpose[{Most[id = IntegerDigits[n]], Rest[id]}] // IntegerDigits // Flatten // FromDigits; Table[a[n], {n, 0, 119}] (* Jean-Fran├žois Alcover, Apr 05 2013 *)

PROG

(Haskell)

a053392 :: Integer -> Integer

a053392 n = if ys == "" then 0 else read ys where

   ys = foldl (++) "" $ map show $ zipWith (+) (tail ds) ds

   ds = (map (read . return) . show) n

-- Reinhard Zumkeller, Nov 26 2013

CROSSREFS

Cf. A053393, A060630, A1003117, A194429.

Sequence in context: A117230 A093882 A138953 * A114925 A043270 A089898

Adjacent sequences:  A053389 A053390 A053391 * A053393 A053394 A053395

KEYWORD

nonn,easy,nice,base,look

AUTHOR

N. J. A. Sloane, Jan 07 2000

STATUS

approved

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Last modified May 24 18:18 EDT 2017. Contains 286997 sequences.