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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A028503 Numbers k such that k*(k+2) is a palindrome. 3
 0, 1, 2, 9, 17, 23, 64, 75, 99, 191, 204, 999, 1747, 1907, 2365, 2966, 5731, 9999, 18991, 20564, 99999, 174601, 174747, 179317, 243063, 293786, 552101, 999999, 1868287, 2967032, 9200156, 9999999, 22765895, 31552659, 93809716, 99999999, 185812387, 999999999 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Giovanni Resta, Table of n, a(n) for n = 1..53 P. De Geest, Palindromic quasipronic numbers of the form n(n+2) FORMULA a(n) = A070253(n) - 1. a(n) * (a(n) + 2) = A028504(n). - Giovanni Resta, Aug 29 2018 MATHEMATICA palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; Select[Range[0, 10^5], palQ[# (# + 2)] &] (* Giovanni Resta, Aug 29 2018 *) CROSSREFS Cf. A005563, A028504, A070253. Sequence in context: A334193 A200944 A137189 * A100291 A126082 A083707 Adjacent sequences:  A028500 A028501 A028502 * A028504 A028505 A028506 KEYWORD nonn,base AUTHOR EXTENSIONS More terms from Giovanni Resta, Aug 28 2018 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.

Last modified June 24 07:45 EDT 2021. Contains 345416 sequences. (Running on oeis4.)