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A230354 Even numbers n such that digit sum of n = digit sum of largest odd divisor of n. 3

%I #7 Oct 16 2013 15:33:10

%S 12,18,36,54,60,72,90,108,126,132,144,156,162,180,198,204,216,228,234,

%T 240,252,270,276,306,320,324,342,348,360,372,378,396,414,420,432,450,

%U 504,516,522,540,558,594,612,624,630,636,660,702,708,720,732,738,756,774,780,792,810,900

%N Even numbers n such that digit sum of n = digit sum of largest odd divisor of n.

%e Largest odd divisor of 162 is 81. Digit_sum(162)=9, digit_sum(81)=9

%o (PARI)

%o mdi(n)= n / 2^valuation(n, 2)

%o digsum(n)={local (d, p); d=0; p=n; while(p, d+=p%10; p=floor(p/10)); return(d)}

%o {for (n=2, 10^3,m=mdi(n);if(digsum(n)==digsum(mdi(n))&&m<>n,print(n)));}

%Y Cf. A006753, A219340, A230355, A230356, A230357.

%K nonn,base,less

%O 1,1

%A _Antonio Roldán_, Oct 16 2013

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