A153211 - OEIS

A153211

Sum of digits of n, times digital reversal of sum of digits of n.

1, 4, 9, 16, 25, 36, 49, 64, 81, 1, 4, 9, 16, 25, 36, 49, 64, 81, 10, 4, 9, 16, 25, 36, 49, 64, 81, 10, 121, 9, 16, 25, 36, 49, 64, 81, 10, 121, 252, 16, 25, 36, 49, 64, 81, 10, 121, 252, 403, 25, 36, 49, 64, 81, 10, 121, 252, 403, 574, 36, 49, 64, 81, 10, 121, 252, 403, 574

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OFFSET

1,2

COMMENTS

The fixed points of this sequence {n such that a(n) = n} are A110921.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = SOD(n)*R(SOD(n)) = A007953(n)*A004086(A007953(n)).

EXAMPLE

a(19) = (1+9)*R(1+9) = 10*01 = 10*1 = 10. a(79) = 976 because (7+9)*R(7+9) = 16*61 = 976.

MATHEMATICA