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Numbers n such that the concatenation of consecutive increasing numbers beginning with Harshad(n) and ending with Harshad(n+1) is a Harshad number; or n such that A112131(n) is a Harshad number.
2

%I #3 Dec 15 2017 17:36:53

%S 1,4,9,10,21,45,48,100,102,135,144,201,228,315,320,378,399,408,736,

%T 792,803,820,832,1000,1035,1044,1056,1088,1101,1128,1215,1233,1308,

%U 1431,1720,1908,1926,1962,2001,2028,2052,2119,2208,2210,2223,2241,2618,2620

%N Numbers n such that the concatenation of consecutive increasing numbers beginning with Harshad(n) and ending with Harshad(n+1) is a Harshad number; or n such that A112131(n) is a Harshad number.

%e a(5)=21 because 2+1+2+2+2+3+2+4 = 18 and 21222324/18 = 1179018.

%Y Cf. A005349.

%K base,nonn

%O 1,2

%A _Jason Earls_, Aug 27 2005