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%I #44 Sep 08 2022 08:46:23
%S 1,2,3,4,5,6,12,16,17,33,34,48,54,285,333,334,365,385,430,471,516,816,
%T 1049,3333,3334,33333,33334,333333,333334,483048,3333333,3333334,
%U 33333333,33333334,333333333,333333334,3333333333,3333333334,33333333333,33333333334
%N Positive integers k such that A270710(k) (= (k+1)*(3*k-1)) have only 1 or 2 different digits in base 10.
%H Giovanni Resta, <a href="/A322570/b322570.txt">Table of n, a(n) for n = 1..50</a>
%F For k > 0, A002277(k) is a term.
%F For k >= 0, A002277(k) + 1 (= A093137(k)) is a term.
%t Select[Range@ 50000, Length@ Union@ IntegerDigits[3 #^2 + 2 # - 1] <= 2 &] (* _Giovanni Resta_, Sep 04 2019 *)
%o (PARI) for(k=1, 1e8, if(#Set(digits(3*k^2+2*k-1))<=2, print1(k", ")))
%o (Magma) [k:k in [1..10000000]| #Set(Intseq((k+1)*(3*k-1))) le 2]; // _Marius A. Burtea_, Aug 29 2019
%Y Cf. A002277, A016069, A093137, A213517 (in case of triangular numbers), A270710, A322571.
%K nonn,base
%O 1,2
%A _Seiichi Manyama_, Aug 29 2019
%E a(35)-a(36) from _Jinyuan Wang_, Aug 30 2019
%E a(37)-a(40) from _Giovanni Resta_, Sep 04 2019