A096347 Least number with n preimages (or immediate predecessors) under f(n) = n + (product of nonzero digits of n).

1, 2, 12, 102, 116, 1098, 2072, 1014, 101134, 11014, 1011098, 1003525, 41021255, 210110985, 403130555, 481104655, 4401225555, 4811125555, 86413249555, 39011218055

Offset

0,2

Comments

First occurrence of k in A096972.

a(20) > 10^11. [From Donovan Johnson, Nov 22 2009]

References

P. A. Loomis, An Introduction to Digit Product Sequences (see link).

Links

Table of n, a(n) for n=0..19.

P. A. Loomis, An Interesting Family of Iterated Sequences.

P. A. Loomis, An Introduction to Digit Product Sequences, J. Rec. Math., 32 (2003-2004), 147-151.

P. A. Loomis, An Introduction to Digit Product Sequences, J. Rec. Math., 32 (2003-2004), 147-151. [Annotated archived copy]

Index entries for Colombian or self numbers and related sequences

Example

a(3)=102 because 102 is the least number with three direct predecessors, 66: 66+6*6 = 102, 74: 74+7*4 = 102, 101: 101+1*1 = 102.

Crossrefs

Cf. A096972, A063108, A063425, A096922, A096923, A096924, A096925, A096926, A096927, A096928, A096929, A096930, A096931.

Sequence in context: A085389 A202013 A151505 * A137483 A113557 A245266

Adjacent sequences: A096344 A096345 A096346 * A096348 A096349 A096350

Keyword

base,more,nonn

Author

Jason Earls, Jun 29 2004

Extensions

a(8) to a(11) from Klaus Brockhaus, Jul 07 2004

a(12) from Robert G. Wilson v, Jul 15 2004

a(13)-a(19) from Donovan Johnson, Nov 22 2009

Status

approved