A058442 -id:A058442 - cp's OEIS frontend

A058441 Numbers k such that k^2 contains only digits {0,4,8}, not ending with zero.

2, 22, 202, 298, 2002, 2022, 2202, 20002, 20022, 22002, 28998, 200002, 200022, 200202, 202002, 220002, 632522, 2000002, 2000022, 2000202, 2020002, 2020022, 2200002, 2200202, 20000002, 20000022, 20000202, 20002002, 20002022, 20002202

Offset: 1

Patrick De Geest, Nov 15 2000

Zhao Hui Du, Table of n, a(n) for n = 1..4000
Patrick De Geest, Index to related sequences
Hisanori Mishima, Sporadic tridigital solutions
Zhao Hui Du, All data no more than 30 digits

Cf. A058442.

A119075 Triangular numbers composed of digits {0,4,8}.

Original entry on oeis.org

80080840, 4448084040, 804844884480, 4448404804004804800840804848000, 44804084840840840848040408400000

Offset: 1

Giovanni Resta, May 10 2006

a(6) > 10^37. - Max Alekseyev, May 17 2009

a(6) > 10^40. - Tyler Busby, Mar 28 2023

Giovanni Resta, Tridigital Triangular Numbers.

Cf. A000217, A058442, A119076. See A119033 for a table of cross-references.

[t: n in [1..2*10^7] | Set(Intseq(t)) subset {0, 4, 8} where t is n*(n+1) div 2]; // Vincenzo Librandi, Dec 18 2015

Rest[Select[FromDigits/@Tuples[{0, 4, 8}, 12], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &]] (* Vincenzo Librandi, Dec 18 2015 *)

a(n) = A000217(A119076(n)). - Michel Marcus, Mar 27 2023

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A058441 Numbers k such that k^2 contains only digits {0,4,8}, not ending with zero.

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A119075 Triangular numbers composed of digits {0,4,8}.

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