A247468 Smallest number m such that A247462(m) = n.

1, 5, 164, 501, 7364, 29121, 515504, 2445693, 92781321

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Formula

A247462(a(n)) = n and A247462(m) < n for m < a(n).

Example

.  n |    a(n) |                  A058977 trajectory
. ---+---------+---------------------------------------------------------
.  2 |       5 | 1/a(2)-5/2-7
.  3 |     164 | 1/a(3)-19/3-13/2-4
.  4 |     501 | 1/a(4)-253/2-25/3-9/2-11
.  5 |    7364 | 1/a(5)-499/3-253/2-25/3-9/2-11
.  6 |   29121 | 1/a(6)-14563/2-979/3-493/2-19/3-13/2-4
.  7 |  515504 | 1/a(6)-34375/3-17191/2-535/3-271/2-23/3-15/2-17
.  8 | 2445693 | 1/a(8)-1222849/2-58241/3-14563/2-979/3-493/2-19/3-13/2-4

Prog

(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a247468 = (+ 1) . fromJust . (`elemIndex` a247462_list)
(PARI) f2(p, q) = my(f=factor(p+q)[, 1]~); vecsum(f)/#f;
f1(r) = f2(numerator(r), denominator(r));
loop(list) = {my(v=Vecrev(list)); for (i=2, #v, if (v[i] == v[1], return(1)); ); }
f(n) = {my(ok=0, m=f2(n, 1), list=List(), nb=1); while(denominator(m) != 1, m = f1(m); nb++; listput(list, m); if (loop(list), return (0)); ); return(nb); } \\ A247462
a(n) = my(k=1); while(f(k) != n, k++); k; \\ Michel Marcus, Feb 09 2022

Crossrefs

Cf. A247462, A058977.

Sequence in context: A128068 A197095 A364117 * A304056 A305450 A304702

Adjacent sequences: A247465 A247466 A247467 * A247469 A247470 A247471

Keyword

nonn,more

Author

Reinhard Zumkeller, Sep 17 2014

Extensions

a(9) from Michel Marcus, Feb 09 2022

Status

approved