1,3

Table of n, a(n) for n=1..72.

E.g. 81^2 = 6561 is not OK since the two digits 6 are separated by the 5. Square 88^2 or 7744 is OK since digits 7 and 4 are grouped.

Cf. A052082, A052085, A052086, A052083, A052084.

Sequence in context: A241158 A241157 A010784 * A031995 A023752 A048737

Adjacent sequences: A052078 A052079 A052080 * A052082 A052083 A052084

nonn,base

Patrick De Geest, Jan 15 2000.

approved