A290227 Numbers n such that A290223(n) = 11.

8, 17, 26, 29, 35, 38, 47, 56, 65, 74, 83, 92, 149, 158, 167, 197

Offset

1,1

Comments

This sequence is believed to be finite. If it exists, a(17) > 10^5.

Links

Table of n, a(n) for n=1..16.

Example

26 is in this sequence because 26 - (2+6)^2 = -38. Then -38 + (3+8)^2 = 83. Then 83 - (8+3)^2 = -38, and so on.

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)==11, print1(n, ", ")))

Crossrefs

Cf. A007953, A003132, A290223.

Sequence in context: A041831 A041122 A042211 * A277052 A305496 A338090

Adjacent sequences: A290224 A290225 A290226 * A290228 A290229 A290230

Keyword

nonn,base,fini,full

Author

Derek Orr, Jul 24 2017

Status

approved