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a(1) = 42; a(n+1) = a(n) + sum of decimal digits of a(n).
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%I #14 Dec 25 2021 18:35:23

%S 42,48,60,66,78,93,105,111,114,120,123,129,141,147,159,174,186,201,

%T 204,210,213,219,231,237,249,264,276,291,303,309,321,327,339,354,366,

%U 381,393,408,420,426,438,453,465,480,492,507,519,534,546,561,573,588,609,624,636

%N a(1) = 42; a(n+1) = a(n) + sum of decimal digits of a(n).

%D D. R. Kaprekar, The Mathematics of the New Self Numbers, Privately Printed, 311 Devlali Camp, Devlali, India, 1963.

%H Reinhard Zumkeller, <a href="/A249043/b249043.txt">Table of n, a(n) for n = 1..10000</a>

%H D. R. Kaprekar, <a href="/A003052/a003052_2.pdf">The Mathematics of the New Self Numbers</a> [annotated and scanned]

%H <a href="/index/Coi#Colombian">Index entries for Colombian or self numbers and related sequences</a>

%F a(n+1) = A062028(a(n)). - _Reinhard Zumkeller_, Oct 31 2014

%o (Haskell)

%o a249043 n = a249043_list !! (n-1)

%o a249043_list = iterate a062028 42

%o -- _Reinhard Zumkeller_, Oct 31 2014

%Y Cf. A004207, A016052, A007618, A006507, A016052, A036228.

%Y Cf. A007953, A062028.

%K easy,nonn,base

%O 1,1

%A _N. J. A. Sloane_, Oct 30 2014