A053899 Squares composed of digits {1,4,7}.

1, 4, 144, 441, 1444, 7744, 7447441, 4147177477444, 7174474747441, 1447471174444717444, 117747174771111771147177144441, 7174471471414771441747147717441, 1147111747441771474111741117114417444, 4741471777144414774147714111744447747417744

Offset: 1

Author

Patrick De Geest, Mar 15 2000

Keywords

• nonn
• base

Links

• Author?, Source(txt)
• P. De Geest, Squares containing at most three distinct digits, Index entries for related sequences
• H. Mishima, Sporadic tridigital solutions

Crossrefs

Cf. A053898.

Formula

a(n) = A053898(n)^2.

Extensions

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005

Four more terms from Mishima's webpage added by Max Alekseyev, Jan 28 2012