A350867 Non-palindromic numbers k for which d(k) = d(R(k)), where R(k) is the reversal of k and d(k) is the number of divisors of k.

13, 15, 17, 24, 26, 31, 37, 39, 42, 51, 58, 62, 71, 73, 79, 85, 93, 97, 107, 113, 115, 117, 122, 123, 129, 143, 149, 155, 157, 158, 159, 165, 167, 169, 177, 178, 179, 183, 185, 187, 199, 203, 205, 221, 226, 246, 264, 265, 285, 286, 288, 294, 302, 311, 314, 319

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Example

264 and 462 are non-palindromic and also d(264) = 16 = d(462), and so both are members.

Prog

(PARI) isok(k) = my(R = fromdigits(Vecrev(digits(k)))); R != k && numdiv(R) == numdiv(k);
(Python)
from sympy import divisor_count as d
def ok(k): Rk = int(str(k)[::-1]); return Rk != k and d(k) == d(Rk)
print([k for k in range(320) if ok(k)]) # Michael S. Branicky, Feb 20 2022

Crossrefs

Cf. A000005 (d), A004086 (R).

Intersection of A029742 and A062895.

Sequence in context: A302440 A031060 A120129 * A354745 A341329 A109019

Adjacent sequences: A350864 A350865 A350866 * A350868 A350869 A350870

Keyword

base,nonn,easy

Author

Daniel Tsai, Feb 18 2022

Status

approved