A355550 a(n) is the smallest number k such that k occurs in the Reverse-and-Multiply trajectories of exactly n positive integers less than k.

0, 4, 16, 1300, 976, 40300, 662704, 12251200

Offset

0,2

Comments

Smallest k such that A355549(k) = n.

Links

Table of n, a(n) for n=0..7.

Prog

(PARI) revmult(n) = n*eval(concat(Vecrev(Str(n))))
a355549(n) = my(i=0); for(k=2, n-1, my(x=k); while(x < n, if(x==revmult(x), break, x=revmult(x))); if(x==n, i++)); i
a(n) = for(k=0, oo, if(a355549(k)==n, return(k)))

Crossrefs

Cf. A355548, A355549.

Sequence in context: A144177 A300315 A361196 * A296628 A123234 A198297

Adjacent sequences: A355547 A355548 A355549 * A355551 A355552 A355553

Keyword

nonn,base,hard,more

Author

Felix Fröhlich, Jul 06 2022

Extensions

a(5)-a(7) from Jinyuan Wang, Jul 07 2022

Status

approved