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A028564
Numbers k such that k*(k+7) is a palindrome.
2
0, 1, 4, 19, 26, 219, 664, 902, 2109, 2972, 2982, 9002, 21009, 29696, 90002, 210009, 223114, 292967, 669024, 900002, 942997, 2100009, 2109664, 2219779, 8972876, 9000002, 21000009, 21037924, 21117304, 21152824, 21155344, 28867722, 29802897, 29857886, 90000002
OFFSET
1,3
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..49
Erich Friedman, What's Special About This Number? (See entries 664, 902, 2109, 2982, 9002.)
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+7)):
yield k
print(list(islice(agen(), 26))) # Michael S. Branicky, Jan 26 2022
CROSSREFS
Sequence in context: A296602 A022135 A192193 * A282506 A047715 A003338
KEYWORD
nonn,base
EXTENSIONS
a(32) and beyond from Michael S. Branicky, Jan 26 2022
STATUS
approved