A028559 Palindromes of the form k*(k+5).

0, 6, 66, 414, 696, 41814, 42224, 666666, 4282824, 4754574, 4881884, 416343614, 630939036, 4159669514, 6817557186, 42877777824, 4163250523614, 4783601063874, 4986733376894, 47431877813474, 6333914444193336, 44653247574235644, 62141509790514126

Offset

1,2

Links

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

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

Formula

a(n) = A028558(n) * (A028558(n) + 5). - Michael S. Branicky, Jan 30 2022

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*(k+5)
print(list(islice(agen(), 20))) # Michael S. Branicky, Jan 30 2022

Crossrefs

Cf. A028557, A028558.

Sequence in context: A185253 A192089 A119073 * A249639 A163699 A062184

Adjacent sequences: A028556 A028557 A028558 * A028560 A028561 A028562

Keyword

nonn,base

Author

Patrick De Geest

Extensions

a(21) and beyond from Michael S. Branicky, Jan 30 2022

Status

approved