OFFSET
1,5
COMMENTS
In the first 500000 terms the largest value is a(443314) = 17. See the examples.
See A369357 for the numbers that terminate the series with lengths >= 1.
LINKS
Scott R. Shannon, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1) = 1 as the series when starting at 1 is 1, 7, and there is no number k such that k - 7 = sopfr(k + 7).
a(2) = 0 as there is no number k such that k - 2 = sopfr(k + 2).
a(5) = 2 as the series when starting at 5 is 5, 13, 23, and there is no number k such that k - 23 = sopfr(k + 23).
a(443314) = 17 as the series when starting at 443314 is 443314, 454409, 454790, 455085, 456828, 474078, 474578, 482330, 482497, 483143, 486180, 486225, 534858, 535155, 535369, 540494, 580542, 581003, and there is no number k such that k - 581003 = sopfr(k + 581003).
CROSSREFS
KEYWORD
nonn
AUTHOR
Scott R. Shannon, Jan 25 2024
STATUS
approved