login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A028555 Numbers n such that n*(n + 4) is a palindrome. 0
0, 1, 7, 14, 21, 33, 44, 144, 235, 269, 524, 1123, 1452, 1582, 5412, 8338, 8459, 11063, 11223, 23255, 73491, 145544, 262808, 266737, 281349, 1659022, 2705669, 3504083, 5040882, 7395091, 8308388, 14554452 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..32.

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

Erich Friedman, What's Special About This Number? (See entries 1452, 1582, 5412, 8338, 8459.)

MATHEMATICA

Select[Range[0, 9999], PalindromeQ[#^2 + 4#] &] (* Alonso del Arte, Nov 10 2019 *)

PROG

(Scala) def palQ(n: Int, b: Int = 10): Boolean = n - Integer.parseInt(n.toString.reverse) == 0

(0 to 9999).filter((n: Int) => palQ(n * n + 4 * n)) // Alonso del Arte, Nov 10 2019

CROSSREFS

Cf. A028336.

Sequence in context: A189931 A164005 A100451 * A061823 A018890 A118502

Adjacent sequences:  A028552 A028553 A028554 * A028556 A028557 A028558

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 23 14:55 EST 2020. Contains 332164 sequences. (Running on oeis4.)