A058438 -id:A058438 - cp's OEIS frontend

A058437 Numbers k such that k^2 contains only digits {0,4,6}, not ending with zero.

2, 8, 20992, 21602, 215408, 800037502, 21120134092, 25815899102, 80025400008, 8000254000008, 25815577558262, 254166490010002, 254243985975008, 683085646609592, 800002540000008, 80000025400000008, 635613598504629262, 2457776365832743262, 2542962918459579238

Offset: 1

Patrick De Geest, Nov 15 2000

Zhao Hui Du, Table of n, a(n) for n = 1..25
P. De Geest, Index to related sequences
Hisanori Mishima, Sporadic tridigital solutions

Cf. A058438.

a(16) and above from Zhao Hui Du, Mar 08 2024

A119073 Triangular numbers composed of digits {0,4,6}.

Original entry on oeis.org

6, 66, 406, 666, 66066, 446040, 600060, 46046406, 440466040, 4040600460, 6604444400406, 4440066066400004040, 644006046066000066046, 44464646466606404046664666, 464440406444064040044646006604604066, 660466006640066446666000606004066646, 60404640400640406040004460664400044060

Offset: 1

Giovanni Resta, May 10 2006

Giovanni Resta, Tridigital Triangular Numbers.

Cf. A000217, A058438, A119074.

See A119033 for a table of cross-references.

[t: n in [1..2*10^7] | Set(Intseq(t)) subset {0,4,6} where t is n*(n+1) div 2]; // Vincenzo Librandi, Dec 18 2015

Rest[Select[FromDigits/@Tuples[{0, 4, 6}, 10], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &]] (* Vincenzo Librandi, Dec 18 2015 *)

a(n) = A000217(A119074(n)). - Tyler Busby, Mar 27 2023

a(15)-a(16) from Max Alekseyev, May 10 2009

a(17) from Tyler Busby, Mar 27 2023

cp's OEIS Frontend

A058437 Numbers k such that k^2 contains only digits {0,4,6}, not ending with zero.

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A119073 Triangular numbers composed of digits {0,4,6}.

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