A290226 Numbers n such that A290223(n) = 2.

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

Offset

1,1

Comments

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

Links

Table of n, a(n) for n=1..8.

Example

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

Prog

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

Crossrefs

Cf. A007953, A003132, A290223.

Sequence in context: A031915 A247603 A102385 * A214596 A226490 A217113

Adjacent sequences: A290223 A290224 A290225 * A290227 A290228 A290229

Keyword

nonn,base,fini,full

Author

Derek Orr, Jul 24 2017

Status

approved