A028337 Palindromes of the form n(n+1).

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

Author

Patrick De Geest

Keywords

• nonn
• base

Examples

			272 belongs to the sequence as 272 = 16*17 is a palindrome.
		

Links

• Patrick De Geest, Palindromic pronic numbers of the form n(n+1)
• Eric Weisstein's World of Mathematics, Palindromic Number.
• Eric Weisstein's World of Mathematics, Pronic Number.

Crossrefs

Cf. A028336.

Programs

Mathematica

Select[2*Accumulate[Range[15820000]],IntegerDigits[#] == Reverse[ IntegerDigits[#]]&] (* Harvey P. Dale, Sep 03 2013 *)

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

Extensions

a(20)-a(23) from G. C. Greubel, Nov 04 2017