A355550 -id:A355550 - cp's OEIS frontend

A355548 a(n) is the smallest number k such that k occurs in the Reverse-and-Add trajectories of exactly n positive integers less than k.

0, 2, 4, 8, 16, 33, 55, 404, 44, 646, 99, 66, 848, 909, 888, 110, 88, 1090, 132, 176, 1089, 363, 3443, 10010, 121, 1881, 242, 1991, 4323, 3982, 1595, 726, 3553, 2992, 3663, 7447, 484, 1353, 46064, 6446, 5665, 10769, 3993, 2662, 4103, 2882, 968, 1111, 1837, 7667

Offset: 0

Felix Fröhlich, Jul 06 2022

a(n) is the smallest k such that A298972(k) = n.

Cf. A298972, A355550.

a298972(n) = my(i=0); for(k=1, n-1, my(x=k); while(x < n, x=x+eval(concat(Vecrev(Str(x))))); if(x==n, i++)); i
a(n) = for(k=0, oo, if(a298972(k)==n, return(k)))

More terms from Jinyuan Wang, Jul 07 2022

A355549 Number of positive integers k with 1 < k < n such that n occurs in the Reverse-and-Multiply trajectory of k.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0

Offset: 0

Felix Fröhlich, Jul 06 2022

Cf. A355550.

revmult(n) = n*eval(concat(Vecrev(Str(n))))
a(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

cp's OEIS Frontend

A355548 a(n) is the smallest number k such that k occurs in the Reverse-and-Add trajectories of exactly n positive integers less than k.

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