A055016 Smallest number whose sum of squares of digits is n.

0, 1, 11, 111, 2, 12, 112, 1112, 22, 3, 13, 113, 222, 23, 123, 1123, 4, 14, 33, 133, 24, 124, 233, 1233, 224, 5, 15, 115, 1115, 25, 125, 1125, 44, 144, 35, 135, 6, 16, 116, 1116, 26, 45, 145, 335, 226, 36, 136, 1136, 444, 7, 17, 117, 46, 27, 127, 1127, 246

Offset

0,3

Links

Zak Seidov, Table of n, a(n) for n = 0..600

E. Angelini, Sum of squares -- and a concatenation, SeqFan list, June 23, 2015.

Prog

(PARI) A055016(n, q=9, m)={ n>1||return(n); forstep(q=min(sqrtint(n), q), 1, -1, m && n \ q^2 * #Str(q) > #Str(m) && break; t=eval(Str(A055016(n-q^2, q), q)); (!m || t<m) && m=t); m } \\ M. F. Hasler, Jun 24 2015

Crossrefs

Cf. A003132 is inverse in sense that n=A003132(a(n)), though not necessarily a(A003132(n)).

Sequence in context: A281601 A266513 A356329 * A259372 A348871 A004287

Adjacent sequences: A055013 A055014 A055015 * A055017 A055018 A055019

Keyword

base,nonn,changed

Author

Henry Bottomley, May 31 2000

Status

approved