

A083818


Numbers n such that 2n1 is the digit reversal of n.


2



1, 37, 397, 3997, 39997, 399997, 3999997, 39999997, 399999997, 3999999997, 39999999997, 399999999997, 3999999999997, 39999999999997, 399999999999997, 3999999999999997, 39999999999999997, 399999999999999997, 3999999999999999997, 39999999999999999997
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OFFSET

1,2


COMMENTS

a(n) = 1 + 36 + 360 + 3600 + 36000 + ..., for a total of n terms. a(n) = 1 + sum of first n1 terms of the geometric progression with first term 36 and common ratio 10. a(n) = 1 + 36*A000042(n1) (the unary sequence).


LINKS

Table of n, a(n) for n=1..20.
Index entries for linear recurrences with constant coefficients, signature (11,10).


FORMULA

a(n) = 4*10^(n1)  3.


EXAMPLE

2*37  1 = 73.


CROSSREFS

Cf. A083811, A083812, A083813.
Digit reversals are A169830.
Sequence in context: A264626 A201789 A115926 * A090023 A254682 A232251
Adjacent sequences: A083815 A083816 A083817 * A083819 A083820 A083821


KEYWORD

base,easy,nonn


AUTHOR

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003


EXTENSIONS

a(1)=1 inserted by David Radcliffe, Jul 25 2015


STATUS

approved



