%I #5 Jul 24 2017 12:31:39

%S 2,23,62,77,119,194,287,398

%N Numbers n such that A290223(n) = 2.

%C This sequence is believed to be finite. a(9) > 10^5, if it exists.

%e 62 is in this sequence because 62 - (6+2)^2 = -2. Then -2 + (2)^2 = 2.

%o (PARI)

%o a(n)=k=n; c=1; v=List(); listput(v, k); while(c, if(k>=0, k-=sumdigits(k)^2; c+=1; if(k==2||k==3||k==0||k==6||k==9, return(k)); if(vecsearch(Vec(v), k), return(sumdigits(abs(k)))); listput(v, k)); if(k<0, k+=sumdigits(-k)^2; c+=1; if(k==2||k==3||k==0||k==6||k==9, return(k)); if(vecsearch(Vec(v), k), return(sumdigits(abs(k)))); listput(v, k)); c+=1)

%o for(n=1,10^5,if(a(n)==2,print1(n,", ")))

%Y Cf. A007953, A003132, A290223.

%K nonn,base,fini,full

%O 1,1

%A _Derek Orr_, Jul 24 2017