A243025 Fixed points of the transform n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + ... + d_(2)*10 + d_(1) -> Sum_{i=1..k-1}{d_(i)^d(i+1)}+d(k)^d(1) (A243023).

1, 4155, 4355, 1953504, 1954329, 522169982

Offset

1,2

Comments

Subset of A243023.

This sequence is finite by using the same argument that Armstrong numbers (A005188) are finite. - Robert G. Wilson v, Jun 01 2014

Links

Table of n, a(n) for n=1..6.

Example

1^1 = 1.
5^5 + 5^1 + 1^4 + 4^5 = 4155.
5^5 + 5^3 + 3^4 + 4^5 = 4355.
4^0 + 0^5 + 5^3 + 3^5 + 5^9 + 9^1 + 1^4 = 1953504.
9^2 + 2^3 + 3^4 + 4^5 + 5^9 + 9^1 + 1^9 = 1954329.

Maple

with(numtheory): P:=proc(q) local a, b, k, ok, n; for n from 10 to q do a:=[]; b:=n;
while b>0 do a:=[op(a), b mod 10]; b:=trunc(b/10); od; b:=0; ok:=1; for k from 2 to nops(a)
do if a[k-1]=0 and a[k]=0 then ok:=0; break; else b:=b+a[k-1]^a[k]; fi; od;
if ok=1 then if n=(b+a[nops(a)]^a[nops(1)]) then print(n);
fi; fi; od; end: P(10^10);

Mathematica

fQ[n_] := Block[{r = Reverse@ IntegerDigits@ n}, n == Plus @@ (r^RotateLeft@ r)]; k = 1; lst = {}; While[k < 1000000001, If[ fQ@ k, AppendTo[ lst, k]; Print@ k]; k++] (* Robert G. Wilson v, Jun 01 2014 *)

Crossrefs

Cf. A243023, A243024.

Cf. A005188, A003321.

Sequence in context: A052464 A161752 A145205 * A196494 A104824 A168663

Adjacent sequences: A243022 A243023 A243024 * A243026 A243027 A243028

Keyword

nonn,base,fini,full

Author

Paolo P. Lava, May 29 2014

Extensions

Added a(1) as 1 and a(6) by Robert G. Wilson v, Jun 01 2014

Status

approved