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A006507
a(n+1) = a(n) + sum of digits of a(n), with a(1)=7.
(Formerly M4348)
20
7, 14, 19, 29, 40, 44, 52, 59, 73, 83, 94, 107, 115, 122, 127, 137, 148, 161, 169, 185, 199, 218, 229, 242, 250, 257, 271, 281, 292, 305, 313, 320, 325, 335, 346, 359, 376, 392, 406, 416, 427, 440, 448, 464, 478, 497, 517, 530, 538, 554, 568
OFFSET
1,1
COMMENTS
a(n) = A004207(n+4) for n > 11. - Reinhard Zumkeller, Oct 14 2013
REFERENCES
Editorial Note, Popular Computing (Calabasas, CA), Vol. 4 (No. 37, Apr 1976), p. 12.
GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 36.
D. R. Kaprekar, Puzzles of the Self-Numbers. 311 Devlali Camp, Devlali, India, 1959.
D. R. Kaprekar, The Mathematics of the New Self Numbers, Privately Printed, 311 Devlali Camp, Devlali, India, 1963.
Jeffrey Shallit, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
FORMULA
a(n) = A062028(a(n-1)) for n > 1. - Reinhard Zumkeller, Oct 14 2013
MATHEMATICA
NestList[#+Total[IntegerDigits[#]]&, 7, 50] (* Harvey P. Dale, Jan 25 2021 *)
PROG
(Haskell)
a006507 n = a006507_list !! (n-1)
a006507_list = iterate a062028 7 -- Reinhard Zumkeller, Oct 14 2013
CROSSREFS
KEYWORD
base,nonn
EXTENSIONS
More terms from Robert G. Wilson v
STATUS
approved