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A193757 Numbers which can be written with their digits in order and using only a plus and a squaring operator. 0
1, 2, 3, 4, 5, 6, 7, 8, 9, 81, 89, 136, 264, 333, 337, 425, 441, 445, 1250, 1251, 1252, 1253, 1254, 1255, 1256, 1257, 1258, 1259, 1306, 1346, 1386, 1521, 1525, 1634, 1636, 1674, 1693, 1745, 2025, 2116, 2225, 2401, 2403, 2407, 2465, 2536, 2576, 2601, 2624 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Erich Friedman calls them S-numbers. It was proved that such numbers are infinitely many but their density is 0.

LINKS

Table of n, a(n) for n=1..49.

Erich Friedman, Problem of the Month, August 2003

EXAMPLE

81 = (8 + 1)^2.

89 = 8 + 9^2.

136 = (1 + 3^2)^2 + 6^2.

264 = 2 + 6 + (4^2)^2.

CROSSREFS

Sequence in context: A272360 A288946 A237346 * A246605 A038178 A023106

Adjacent sequences:  A193754 A193755 A193756 * A193758 A193759 A193760

KEYWORD

nonn,base

AUTHOR

Kausthub Gudipati, Aug 31 2011

STATUS

approved

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Last modified April 5 06:13 EDT 2020. Contains 333238 sequences. (Running on oeis4.)