A028558 Numbers k such that k*(k+5) is a palindrome.

0, 1, 6, 18, 24, 202, 203, 814, 2067, 2178, 2207, 20402, 25116, 64493, 82566, 207067, 2040402, 2187142, 2233097, 6887078, 79585891, 211313148, 249281986, 8161664181, 22222222222, 26331005924, 81294635989

Offset

1,3

Links

Table of n, a(n) for n=1..27.

Patrick De Geest, Palindromic Quasipronics of the form n(n+x)

Erich Friedman, What's Special About This Number? (See entries 814, 2067.)

Prog

(Python)
from itertools import count, islice
def ispal(n): s = str(n); return s == s[::-1]
def agen():
    for k in count(0):
        if ispal(k*(k+5)):
            yield k
print(list(islice(agen(), 20))) # Michael S. Branicky, Jan 24 2022

Crossrefs

Sequence in context: A051395 A256266 A228104 * A337324 A140450 A157800

Adjacent sequences: A028555 A028556 A028557 * A028559 A028560 A028561

Keyword

nonn,base,more

Author

Patrick De Geest

Extensions

a(21)-a(27) from Michael S. Branicky, Jan 24 2022

Status

approved