A343128 Numbers k such that prime(prime(prime(k))) ends in k.

7, 229, 417, 657, 26203, 32553, 50971, 93487, 231221, 17064941, 54784601, 93007099, 981668491, 16040988367, 80362373337, 421408555923, 510995973249, 667162127953, 825773555287

Offset

1,1

Comments

Numbers k such that A038580(k) ends in k. - Michel Marcus, Apr 27 2026

Links

Table of n, a(n) for n=1..19.

Example

417 is a term since prime(prime(prime(417))) = 302417.
26203 is a term since prime(prime(prime(26203))) = 73226203.
From Chai Wah Wu, Apr 14 2021: (Start)
17064941 is a term since prime(prime(prime(17064941))) = 169217064941.
prime(prime(prime(54784601))) = 647454784601,
prime(prime(prime(93007099))) = 1185993007099,
prime(prime(prime(981668491))) = 17148981668491,
prime(prime(prime(16040988367))) = 390416040988367. (End)
From Keiichi Motoi, Apr 28 2026: (Start)
prime(prime(prime(80362373337))) = 2329080362373337,
prime(prime(prime(421408555923))) = 14459421408555923,
prime(prime(prime(510995973249))) = 17869510995973249,
prime(prime(prime(667162127953))) = 23946667162127953,
prime(prime(prime(825773555287))) = 30258825773555287. (End)

Prog

(Python)
A343128_list = [n for n in range(1, 10**4) if n % 2 and n % 5 and prime(prime(prime(n))) % 10**(len(str(n))) == n]

Crossrefs

Cf. A038580, A046883, A074978.

Sequence in context: A157693 A221029 A221495 * A142116 A201955 A081618

Adjacent sequences: A343125 A343126 A343127 * A343129 A343130 A343131

Keyword

nonn,base,more

Author

Chai Wah Wu, Apr 06 2021

Extensions

a(11)-a(14) from Chai Wah Wu, Apr 14 2021

a(15)-a(19) from Keiichi Motoi, Apr 28 2026

Status

approved