

A298972


Number of positive integers k < n such that n occurs in the ReverseandAdd trajectory of k.


0



0, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 2, 2, 0, 1, 0, 4, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 0, 0, 0, 0, 0, 0, 0
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OFFSET

0,5


COMMENTS

Number of integers k < n such that n occurs in row k of A243238.
For n > 0, a(n) = 0 iff n is a term of A067031.
For n > 0, a(n) > 0 iff n is a term of A067030.


LINKS

Table of n, a(n) for n=0..85.
Index entries for sequences related to Reverse and Add!


EXAMPLE

For n = 22: There exist 4 positive integers k < 22 such that 22 occurs in the ReverseandAdd trajectory of k, namely 5, 10, 11 and 20, so a(22) = 4.


MATHEMATICA

Block[{nn = 85, s}, s = Array[Union@ NestWhileList[# + IntegerReverse@ # &, #, # < nn &, 1, nn] &, nn]; Array[Count[Take[s, #  1], #, 2] &, nn + 1, 0]] (* Michael De Vlieger, Feb 01 2018 *)


PROG

(PARI) a(n) = my(i=0); for(k=1, n1, my(x=k); while(x < n, x=x+eval(concat(Vecrev(Str(x))))); if(x==n, i++)); i


CROSSREFS

Cf. A056964, A067030, A067031, A243238.
Sequence in context: A162515 A175267 A108045 * A143728 A127368 A112552
Adjacent sequences: A298969 A298970 A298971 * A298973 A298974 A298975


KEYWORD

nonn,base


AUTHOR

Felix FrÃ¶hlich, Jan 30 2018


STATUS

approved



