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A028337
Palindromes of the form k*(k + 1).
3
2, 6, 272, 6006, 289982, 2629262, 6039306, 27999972, 28233282, 2704884072, 20278187202, 20591819502, 2592587852952, 2936231326392, 21809166190812, 27237788773272, 229145919541922, 233552101255332, 250087292780052, 2243922442293422, 2570769009670752, 20333113431133302, 27785925652958772
OFFSET
1,1
REFERENCES
Elena Deza and Michel Marie Deza, Figurate numbers, World Scientific Publishing (2012), page 278.
LINKS
Eric Weisstein's World of Mathematics, Palindromic Number.
Eric Weisstein's World of Mathematics, Pronic Number.
EXAMPLE
272 belongs to the sequence as 272 = 16*17 is a palindrome.
MATHEMATICA
Select[2*Accumulate[Range[15820000]], IntegerDigits[#] == Reverse[ IntegerDigits[#]]&] (* Harvey P. Dale, Sep 03 2013 *)
PROG
(Python)
A028337_list, n = [], 0
for i in range(2, 10**6, 2):
n += i
s = str(n)
if s == s[::-1]:
A028337_list.append(n) # Chai Wah Wu, Jan 15 2015
CROSSREFS
Cf. A028336.
Intersection of A002113 and A002378.
Sequence in context: A232696 A007190 A164829 * A215293 A264410 A135014
KEYWORD
nonn,base
EXTENSIONS
a(20)-a(23) from G. C. Greubel, Nov 04 2017
STATUS
approved