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A027580 Palindromes of the form n^2 + (n+1)^2 + (n+2)^2 + (n+3)^2 + (n+4)^2. 2
55, 51015, 554455, 51488415, 510151015, 55883648705050784638855, 531578379527444725973875135 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Terms start and end with the digit 5 since all terms are divisible by 5, i.e., the corresponding values of n are odd (see A027579). - Chai Wah Wu, Jan 18 2016

LINKS

Table of n, a(n) for n=1..7.

P. De Geest, Palindromic Sums of Squares of Consecutive Integers

MATHEMATICA

Select[Table[n^2 + (n + 1)^2 + (n + 2)^2 + (n + 3)^2 + (n + 4)^2, {n, 10^7}], # == Reverse@ # &@ IntegerDigits@ # &] (* Michael De Vlieger, Jan 24 2016 *)

PROG

(Python)

A027580_list = []

for i in range(1, 10**8, 2):

    s = str(5*(i*(i+4)+6))

    if s == s[::-1]:

        A027580_list.append(int(s)) # Chai Wah Wu, Jan 18 2016

CROSSREFS

Cf. A027579.

Sequence in context: A221000 A196428 A231907 * A265980 A287053 A046194

Adjacent sequences:  A027577 A027578 A027579 * A027581 A027582 A027583

KEYWORD

nonn,base,more

AUTHOR

Patrick De Geest

EXTENSIONS

a(6) from Chai Wah Wu, Jan 18 2016

a(7) from Giovanni Resta, Aug 04 2019

STATUS

approved

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Last modified September 22 02:48 EDT 2021. Contains 347605 sequences. (Running on oeis4.)