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A069250 Sum of the reversals of the proper divisors of n. 5
0, 1, 1, 3, 1, 6, 1, 7, 4, 8, 1, 16, 1, 10, 9, 15, 1, 21, 1, 13, 11, 14, 1, 45, 6, 34, 13, 55, 1, 69, 1, 76, 15, 74, 13, 127, 1, 94, 35, 23, 1, 72, 1, 40, 69, 35, 1, 148, 8, 61, 75, 100, 1, 174, 17, 145, 95, 95, 1, 99, 1, 16, 32, 99, 37, 78, 1, 121, 36, 110, 1, 240, 1, 76, 112, 181, 19, 198, 1, 88, 85, 17, 1, 203 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Indranil Ghosh, Table of n, a(n) for n = 1..50000

Pe, J. The Picture-Perfect Numbers

FORMULA

a(n) = A069192(n) - A004086(n). - Indranil Ghosh, Feb 10 2017

EXAMPLE

The proper divisors of 20 are 1,2,4,5,10, which reversed are 1,2,4,5,1, summing to 13. Therefore a(10) = 13.

MATHEMATICA

f[n_] := FromDigits[Reverse[IntegerDigits[n]]]; g[n_] := Apply[Plus, Map[f, Drop[Divisors[n], -1]]]; Table[g[i], {i, 1, 40}]

PROG

(Python)

def A069250(n):

....s=0

....for i in range(1, n):

........if n%i==0: s+=int(str(i)[::-1])

....return s # Indranil Ghosh, Feb 10 2017

CROSSREFS

Cf. A069192, A000203, A004086.

Sequence in context: A248029 A117552 A294886 * A294888 A001065 A173455

Adjacent sequences:  A069247 A069248 A069249 * A069251 A069252 A069253

KEYWORD

base,nonn

AUTHOR

Joseph L. Pe, Apr 19 2002

EXTENSIONS

More terms from N. J. A. Sloane, May 19 2013

STATUS

approved

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Last modified July 7 16:01 EDT 2020. Contains 335496 sequences. (Running on oeis4.)