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A027572
Palindromes of form n^2 + (n+1)^2.
2
1, 5, 181, 313, 545, 1690961, 3162613, 3187813, 5258525, 5824285, 58281418285, 1635446445361, 3166046406613, 124852060258421, 149988757889941, 310433303334013, 582818040818285, 12951570707515921, 5227371841481737225, 5649436330336349465, 5816694029204966185
OFFSET
1,2
COMMENTS
a(50) > 10^40. - Patrick De Geest, May 25 2021
FORMULA
a(n) = (4*m^2 - 4*m + 2)/2 = (m-1)^2 + m^2 or a(n) = (4*n^2 + 4*n + 2)/2 = n^2 + (n+1)^2 with n = m - 1.
CROSSREFS
A050239 is a subsequence.
Sequence in context: A366342 A162136 A053363 * A050239 A218690 A345338
KEYWORD
nonn,base
EXTENSIONS
a(18)-a(21) from Donovan Johnson, Aug 26 2012
a(1)=1 added by Philip Mizzi, Sep 02 2019
a(22)-a(49) from Patrick De Geest, May 25 2021
STATUS
approved