The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A336836 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A336836

Number of iterations of x -> A003961(x) needed before A003961(x) < 2x, when starting from x=n, or -1 if such a number is never reached.
(history; published version)

#22 by Joerg Arndt at Sun Jun 13 03:24:04 EDT 2021

STATUS

reviewed

approved

#21 by Michel Marcus at Sun Jun 13 00:41:48 EDT 2021

STATUS

proposed

reviewed

#20 by Jon E. Schoenfield at Sat Jun 12 23:50:12 EDT 2021

STATUS

editing

proposed

#19 by Jon E. Schoenfield at Sat Jun 12 23:50:10 EDT 2021

NAME

Number of iterations of x -> A003961(x) needed before A003961(x) < 2x, when starting from x=n, or -1 if such a number is never reached.

STATUS

approved

editing

#18 by Susanna Cuyler at Sun Aug 09 00:33:00 EDT 2020

STATUS

proposed

approved

#17 by Antti Karttunen at Sat Aug 08 19:55:27 EDT 2020

STATUS

editing

proposed

#16 by Antti Karttunen at Sat Aug 08 05:36:02 EDT 2020

COMMENTS

Note that in contrast to abundancy used in A336835, the condition [A003961(x) > 2x] (= A252742) is not monotonic when iterating with A003961. For example, we have A003961(9) = 25 > 2*9, A003961(25) = 49 < 2*25, and then again A003961(49) = 121 > 2*49.

#15 by Antti Karttunen at Sat Aug 08 05:33:13 EDT 2020

COMMENTS

Note that in contrast to A336835, the condition [A003961(x) < > 2x ] (= A252742) is not monotonic when iterating with A003961. For example, we have A003961(9) = 25 > 2*9, A003961(25) = 49 < 2*25, and then again A003961(49) = 121 > 2*49.

#14 by Antti Karttunen at Sat Aug 08 05:31:33 EDT 2020

CROSSREFS

Cf. A005940, A246281 (positions of zeros, numbers k for which A003961(k) < 2*k), A252742, A252743, A286385.

Cf. A005940, A252742, A252743, A286385.

#13 by Antti Karttunen at Sat Aug 08 05:30:25 EDT 2020

NAME

Number of iterations of x -> A003961(x) needed before A003961(x) < 2x, when starting from x=n, or -1 if such number is never reached.

COMMENTS

Question: Does this sequence need an escape clause?

Question: Is the escape clause necessary in the definition?