login
A032790
Palindromic quotients (k*(k+1)*(k+2)) / (k+(k+1)+(k+2)).
3
0, 1, 5, 8, 33, 161, 616, 3333, 8008, 18881, 54945, 333333, 33333333, 120232021, 124060421, 161656161, 185464581, 541202145, 677191776, 3333333333, 6316116136, 333333333333, 544721127445, 616947749616, 3333169613333, 3333802083333, 5412843482145, 6352230322536
OFFSET
1,3
COMMENTS
For all i >= 1, 3^{2*i} is a term arising from k = 9^i, where ^ is repeated concatenation. - Michael S. Branicky, Jan 24 2022
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..48
MATHEMATICA
Select[Table[Times@@Range[n, n+2]/(3n+3), {n, 0, 317*10^4}], PalindromeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 06 2019 *)
PROG
(Python)
from itertools import count, islice
def ispal(n): s = str(n); return s == s[::-1]
def agen():
for k in count(0):
q, r = divmod(k*(k+2), 3)
if r == 0 and ispal(q):
yield k, q
print([q for k, q in islice(agen(), 31)]) # Michael S. Branicky, Jan 24 2022
CROSSREFS
Cf. A032789.
Sequence in context: A099631 A199396 A275003 * A187997 A188065 A204676
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, May 15 1998
EXTENSIONS
a(26) and beyond from Michael S. Branicky, Jan 24 2022
STATUS
approved