A028553 -id:A028553 - cp's OEIS frontend

A028554 Palindromes of form n(n+3).

0, 4, 88, 868, 4554, 8008, 45154, 89698, 452254, 4526254, 8996998, 830333038, 862626268, 899969998, 4058008504, 45032023054, 45229592254, 89999699998, 405485584504, 4503764673054, 8187727277818, 8999996999998, 89178266287198, 455467838764554, 833066101660338

Offset: 1

Patrick De Geest

Also: Palindromes that are the sum of consecutive initial even composites. Sequence 4 + 6 + 8 + 10 + 12 + 14 + ... + z = n. For values of z see A058851. (Comment added by author 12/2000).

9*10^(2n)-3*10^n-2 for n >= 0 are terms. For n > 1, the first (and last digit) of a(n) is either 4 or 8. - Chai Wah Wu, Feb 20 2021

Chai Wah Wu, Table of n, a(n) for n = 1..40
P. De Geest, Palindromic Quasipronics
P. De Geest, Palindromic Sums 2

Cf. A028553, A058851.

n, m, A028554_list = 4, 0, []
while n < 10**12:
    s = str(m)
    if s == s[::-1]:
        A028554_list.append(m)
    m += n
    n += 2 # Chai Wah Wu, Feb 20 2021

More terms from Chai Wah Wu, Feb 20 2021

A058851 Sum of even composites up to n is palindromic.

Original entry on oeis.org

4, 18, 58, 134, 178, 424, 598, 1344, 4254, 5998, 57630, 58740, 59998, 127404, 424414, 425344, 599998, 1273554, 4244414, 5722840, 5999998, 18886848, 42683384, 57725768, 59999998, 424650414, 578107368, 588254658, 588349340

Offset: 1

Patrick De Geest, Dec 15 2000

Sequence is 4 + 6 + 8 + 10 + 12 + 14 + ... + n.

6*10^n-2 for n >=0 are terms. - Chai Wah Wu, Feb 20 2021

Chai Wah Wu, Table of n, a(n) for n = 1..40
P. De Geest, Palindromic Sums

Cf. A028553, A028554.

a(n) = 2*(1+A028553(1+n)). - R. J. Mathar, Sep 09 2015

cp's OEIS Frontend

A028554 Palindromes of form n(n+3).

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