Behaviour, 52 bytes
t=&(i=1\~([a%i>a%(i+1)a%i>a%(i-1)]i+=1i<#a-1)i>#a-2) I don't exactly know the rules regarding recently self-made esolangs, but here goes nothing.
Ungolfed and commented:
t = &( i=1 // start on the index 1 // repeat the following sequence until failure \~( // either the ith member is bigger than the previous or bigger than the next [ a%i > a%(i+1) a%i > a%(i-1) ] // increment index and check if it still is less than n-1 i += 1 i < #a-1 ) // is a tower if the index stopped incrementing on the last possible index (i.e. passed all the checks) i > #a-2 ) Test with:
t:{1} t:{1 2 3} t:{3 1 2} Bonus (bigger) answer using more obscure features of the language but basicaly the same logic:
t=&![#a<3[#(t=a)<3(#a-2)*&(v=t%(a+1)[v>t%a;v>t%v>t%a|v<t%(a+2)]))>&(a;b)];>&a|b]