A006507 a(n+1) = a(n) + sum of digits of a(n), with a(1)=7.

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

Author

N. J. A. Sloane

Keywords

• base
• nonn

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).

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• D. R. Kaprekar, The Mathematics of the New Self Numbers [annotated and scanned]
• Index entries for Colombian or self numbers and related sequences

Crossrefs

Cf. A016052, A007618, A016096.

Programs

Haskell

a006507 n = a006507_list !! (n-1)
a006507_list = iterate a062028 7  -- Reinhard Zumkeller, Oct 14 2013

Mathematica

NestList[#+Total[IntegerDigits[#]]&,7,50] (* Harvey P. Dale, Jan 25 2021 *)

Formula

a(n) = A062028(a(n-1)) for n > 1. - Reinhard Zumkeller, Oct 14 2013

Extensions

More terms from Robert G. Wilson v