A262989 Predestined numbers A262743 generated from at least a pair of products in which, for each product, all digits 0 through 9 are used, and each digit appears exactly once.
248665082, 248695370, 249063875, 253674980, 256175640, 257930648, 257938064, 260577504, 260817480, 263987504, 264713960, 267766632, 267953048, 269037548, 269045192, 269174192, 269307584, 269735900, 269937500
Offset: 1
Examples
248665082 = 106*2345897 and 2378*104569; 248695370 = 10*24869537 and 1045*237986, 1045*237986 and 1*248695370; 249063875 = 2375*104869 and 1*249063875; ... 8270423667 = 87*95062341 and 957*8642031; 8271362484 = 957*8643012 and 8526*970134; 8282993378 = 853*9710426 and 8503*974126.
References
- Francesco Di Matteo, Sequenze ludiche, Game Edizioni (2015), page 37.
Links
- Francesco Di Matteo, Table of n, a(n) for n = 1..19
- Andrea Marchini, The first 19 terms calculated
- Andrea Marchini, The last 23 terms calculated
- Andrea Marchini, All the 95009 terms with product pairs, Oct 10 2015.
Programs
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Mathematica
good[w_]:=Block[{L={}}, Do[If[ Length[ Select[ Join[w[[i]], w[[j]]], Mod[#,10]==0&]]<=1,AppendTo[L, {w[[i]], w[[j]]}]], {i, Length@w}, {j, i-1}]; L]; f[w_]:=Select[ Table[ FromDigits/@ {Take[w, i], Take[w, i-10]}, {i, 5}], #[[1]] <= #[[2]] && IntegerLength[#[[1]]] + IntegerLength[ #[[2]]] == 10&]; p = Select[ Permutations@ Range[0, 9], First[#] > 0&]; t = SplitBy[ Sort[{ Times@@ #, #} &/@ Flatten[ f/@ p, 1]], First]; u = Select[ (Last/@ #) &/@ Select[t, Length[#] > 1&], good[#] != {} &]; seq = Union[ Times @@@ Flatten[u, 1]]; Length@ seq (* Giovanni Resta, Oct 07 2015 *)
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