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A322570 Positive integers k such that A270710(k) (= (k+1)*(3*k-1)) have only 1 or 2 different digits in base 10. 3
1, 2, 3, 4, 5, 6, 12, 16, 17, 33, 34, 48, 54, 285, 333, 334, 365, 385, 430, 471, 516, 816, 1049, 3333, 3334, 33333, 33334, 333333, 333334, 483048, 3333333, 3333334, 33333333, 33333334, 333333333, 333333334, 3333333333, 3333333334, 33333333333, 33333333334 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..50

FORMULA

For k > 0, A002277(k) is a term.

For k >= 0, A002277(k) + 1 (= A093137(k)) is a term.

MATHEMATICA

Select[Range@ 50000, Length@ Union@ IntegerDigits[3 #^2 + 2 # - 1] <= 2 &] (* Giovanni Resta, Sep 04 2019 *)

PROG

(PARI) for(k=1, 1e8, if(#Set(digits(3*k^2+2*k-1))<=2, print1(k", ")))

(Magma) [k:k in [1..10000000]| #Set(Intseq((k+1)*(3*k-1))) le 2]; // Marius A. Burtea, Aug 29 2019

CROSSREFS

Cf. A002277, A016069, A093137, A213517 (in case of triangular numbers), A270710, A322571.

Sequence in context: A032885 A023788 A032989 * A108320 A177958 A032941

Adjacent sequences: A322567 A322568 A322569 * A322571 A322572 A322573

KEYWORD

nonn,base

AUTHOR

Seiichi Manyama, Aug 29 2019

EXTENSIONS

a(35)-a(36) from Jinyuan Wang, Aug 30 2019

a(37)-a(40) from Giovanni Resta, Sep 04 2019

STATUS

approved

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Last modified February 6 20:45 EST 2023. Contains 360111 sequences. (Running on oeis4.)