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A238530 Position of first occurrence of n in A238529 (Recursive depth of n modulo sopfr(n)). 2
2, 8, 22, 166, 778, 4962, 29922, 179682, 688078, 7060198, 42361338, 674524645 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

The depth of 22 is 3 because 22->9->3, that is, 22 mod (11 + 2) = 9, 9 mod (3 + 3) = 3, and 3 mod (3) = 0, and 22 is the smallest number to have a depth of 3.

a(10) = 7060198, because 7060198->3530097->392185->78417->8665->1713->565->93->25->5

PROG

(Python)

def primfacs(n):

    i = 2

    primfacs = []

    while i * i <= n:

        while n % i == 0:

            primfacs.append(i)

            n = n / i

        i = i + 1

    if n > 1:

        primfacs.append(n)

    return primfacs

def sopfr(n):

    plist = list(primfacs(n))

    l = len(plist)

    s = 0

    while l > 0:

        s += plist[l - 1]

        l -= 1

    return s

def sd(n):

    d = 1

    s = n % sopfr(n)

    if s > 1:

        d += sd(s)

    return d

n=2

max=1000

rec = 0

lst = []

while n <= max:

    r = sd(n)

    if r > rec:

        lst.append(n)

        rec = r

    n += 1

print(lst)

CROSSREFS

Sequence in context: A300370 A191643 A151356 * A303287 A321068 A158466

Adjacent sequences:  A238527 A238528 A238529 * A238531 A238532 A238533

KEYWORD

nonn,more

AUTHOR

J. Stauduhar, Feb 28 2014

EXTENSIONS

a(12) from Michel Marcus, Mar 26 2014

STATUS

approved

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Last modified July 7 12:47 EDT 2022. Contains 355148 sequences. (Running on oeis4.)