A284046 - OEIS

A284046

Numbers k, not ending in 0, such that the consecutive digits of k^2 differ by 0 or 1.

1, 2, 3, 11, 26, 111, 1111, 11111, 105462, 111111, 460688, 753576, 1111111, 2806538, 3513626, 5858612, 11111111, 23335688, 111111111, 674874474, 8226042716, 2131535935501, 81655720279388

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OFFSET

1,2

COMMENTS

Equivalently, numbers not ending in 0, whose square belong to A032981.

All members k ending in 1 are generators of infinite numbers of the form k*10^e which satisfy the same property. In a sense, here we list only "primitive" terms, not ending in 0.

a(24) > 10^17, if it exists.

LINKS

Table of n, a(n) for n=1..23.

EXAMPLE

81655720279388 belongs to this sequence because the consecutive digits of its square, 6667656654345656676777654544, differ by 0 or 1.

MATHEMATICA

Select[Range[10^6], Mod[#, 10] > 0 && Max@ Abs@ Differences@ IntegerDigits[ #^2] <= 1 &]

CROSSREFS

Cf. A032981, A048412, A079036.

Sequence in context: A229066 A248161 A056851 * A048412 A259428 A002981

Adjacent sequences: A284043 A284044 A284045 * A284047 A284048 A284049

KEYWORD

nonn,base,more

AUTHOR

Giovanni Resta, Mar 19 2017

STATUS

approved