A230357 - OEIS

%I #7 Oct 16 2013 15:34:22

%S 22,94,105,114,136,140,160,166,202,222,234,250,265,274,346,355,361,

%T 382,424,438,445,454,516,517,526,532,562,634,702,706,712,732,812,913,

%U 915,922,1036,1071,1086,1111,1116,1122,1138,1165,1185,1204,1206,1219,1221,1230,1239,1255,1282,1312,1316,1318,1345,1363,1400,1404,1432,1507,1520,1530,1550

%N Numbers n such that digit sum of n equals digit sum of sopf(n) (sum of the distinct prime factors of n).

%e 166=2*83. Sopf(166)=85. Digit_sum(166)=13, digit_sum(85)=13.

%o (PARI)

%o sopf(n)= { local(f, s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]); return(s) }

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

%o {for (n=4, 2*10^3,m=sopf(n);if(digsum(n)==digsum(m)&&m<>n,print(n)))}

%Y Cf. A006753,  A036920, A230354, A230355, A230356.

%K nonn,base,less

%O 1,1

%A _Antonio Roldán_, Oct 16 2013