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%I #15 Oct 05 2020 05:11:00
%S 23256,530712,809100,11692980,17812620,20245500,22834062,23527350,
%T 29154600,83768256,182236500,189847062,506227500,600127506,992218500,
%U 1363566402,1640209500,2175895962,2422657620,2477899062,2520190602,3041687952,3764129256,4760103042
%N Smaller of two consecutive oblong numbers which are anagrams of each other.
%C All terms are multiples of 9.
%C The indices of these oblong numbers are 152, 728, 899, 3419, 4220, 4499, 4778, 4850, 5399, 9152, 13499, 13778, 22499, 24497, 31499, 36926, 40499, 46646, 49220, 49778, 50201, 55151, 61352, 68993.
%e 530712 is in the sequence because it is an oblong number, 530712 = 728 * 729, and the next oblong number, 532170 = 729 * 730, is an anagram of 530712.
%t s = {}; o1 = 1; d1 = Sort @ IntegerDigits[o1]; Do[o2 = n*(n + 1); d2 = Sort @ IntegerDigits[o2]; If[d2 == d1, AppendTo[s, o1]]; o1 = o2; d1 = d2, {n, 2, 70000}]; s (* _Amiram Eldar_, Sep 21 2020 *)
%o (PARI) ok(k) = {my(b, m=0); if(issquare(4*k + 1), b=truncate(sqrt(4*k + 1) - 1)/2; if(vecsort(digits(k)) == vecsort(digits((b + 1)*(b + 2))), m = 1)); m}
%Y Subsequence of A008591.
%Y Cf. A002378, A069567, A227692, A228133, A228135.
%K nonn,base
%O 1,1
%A _Antonio Roldán_, Sep 21 2020