A028565 Palindromes of form k*(k+7).

0, 8, 44, 494, 858, 49494, 445544, 819918, 4462644, 8853588, 8913198, 81099018, 441525144, 882060288, 8100990018, 44105250144, 49781418794, 85831713858, 447597795744, 810009900018, 889249942988, 4410052500144, 4450696960544, 4927434347294, 80512566521508, 81000099000018

Offset

1,2

Links

Michael S. Branicky, Table of n, a(n) for n = 1..49

Patrick De Geest, Palindromic Quasipronics of the form n(n+x)

Formula

a(n) = A028564(n) * (A028564(n) + 7). - Michael S. Branicky, Jan 26 2022

Mathematica

Select[Table[k(k+7), {k, 0, 9000100}], PalindromeQ] (* Harvey P. Dale, Dec 17 2024 *)

Prog

(Python)
from itertools import count, islice
def ispal(n): s = str(n); return s == s[::-1]
def agen():
    for k in count(0):
        if ispal(k*(k+7)):
            yield k*(k+7)
print(list(islice(agen(), 28))) # Michael S. Branicky, Jan 26 2022

Crossrefs

Cf. A028563, A028564.

Sequence in context: A112908 A264819 A350128 * A366338 A129553 A174643

Adjacent sequences: A028562 A028563 A028564 * A028566 A028567 A028568

Keyword

nonn,base

Author

Patrick De Geest

Extensions

a(23) and beyond from Michael S. Branicky, Jan 26 2022

Status

approved