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

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A340164 Rotationally ambigrammatic square numbers with no trailing zeros. 1
 0, 1, 9, 16, 81, 169, 196, 961, 1089, 1681, 6889, 9801, 10609, 10816, 11881, 19881, 61009, 69169, 69696, 80089, 90601, 91809, 110889, 160801, 190096, 190969, 198916, 199809, 609961, 660969, 698896, 811801, 896809, 900601, 910116, 919681, 998001, 1006009 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS A rotationally ambigrammatic number (A045574) is one that can be rotated by 180 degrees resulting in a readable, most often new number. Such numbers, by definition, can only contain the digits 0, 1, 6, 8, 9. If the number once rotated happens to be the same number (e.g., 6889) it is a strobogrammatic number.  Those present here are the terms of A018848. Numbers such as 100, which is a square with trailing zeros, have been excluded. Such numbers rotated by 180 degrees would be written with leading zeros. Typically this is not the way we write numbers. This sequence is infinite as it contains (10^k + 3)^2 and (3*10^k + 1)^2 for any k >= 0 (note also that A004086((10^k + 3)^2) = (3*10^k + 1)^2 when k > 0). - Rémy Sigrist, Dec 30 2020 LINKS Wikipedia, Ambigram FORMULA a(n) = A339996(n)^2. MATHEMATICA Select[Range[0, 1000], (# == 0 || ! Divisible[#, 10]) && AllTrue[IntegerDigits[#^2], MemberQ[{0, 1, 6, 8, 9}, #1] &] &]^2 (* Amiram Eldar, Dec 30 2020 *) PROG (PARI) isra(n) = (n%10) && (!setminus(Set(Vec(Str(n))), Vec("01689"))) || !n; \\ A045574 isok(n) = issquare(n) && isra(n); \\ Michel Marcus, Dec 30 2020 CROSSREFS Intersection of A045574 and A000290. Cf. A004086, A339996 (square roots). Sequence in context: A198308 A167349 A267763 * A308248 A179307 A014720 Adjacent sequences:  A340161 A340162 A340163 * A340165 A340166 A340167 KEYWORD nonn,base,easy AUTHOR Philip Mizzi, Dec 30 2020 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 December 5 10:10 EST 2021. Contains 349543 sequences. (Running on oeis4.)