|
| |
|
|
A112646
|
|
Special solutions to Abs[sigma[x+1]-sigma[x]]=2 where x+1 = 3^y.
|
|
2
| | |
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| The relevant computed exponents providing -1+3^z solutions for A112645 are 2,3,7,13,71,103.
The next term, if it exists, is too large to include here. - N. J. A. Sloane, Jul 12 2009
Contribution from David Wasserman (dwasserm(AT)earthlink.net), Jul 06 2009: No more terms < 10^86.
|
|
|
MATHEMATICA
| ta={{0}}; Do[s=Abs[DivisorSigma[1, 3^n]-DivisorSigma[1, -1+3^n]]; If[Equal[s, 2], ta=Append[ta, n]; Print[ -1+3^n]], {n, 1, 100000000}]; ta=Delete[ta, 1]
|
|
|
CROSSREFS
| Cf. A000203, A112645, A112647.
Sequence in context: A000810 A171740 A129663 * A119522 A070494 A070493
Adjacent sequences: A112643 A112644 A112645 * A112647 A112648 A112649
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Sep 28 2005
|
| |
|
|
