A320880 Primes such that iteration of A062028 (n + its digit sum) yields 8 primes in a row.

56676324799, 373169411809, 2121959132809, 10180781225809, 14328311692789, 17429111275789, 32594135422789, 34327062247789, 39262151325799, 57404320087789, 60760513291789, 63116080460809, 66105224572789, 92054642332789, 98606700040789

Offset: 1

Author

Zak Seidov and M. F. Hasler, Nov 08 2018

Keywords

• nonn
• base

Comments

Term a(1) is immediate to find from the nearly equal terms A320879(7..8); terms a(2..9) were found by G. Resta as answer to Rivera's Puzzle 163, cf. link.

Links

• Carlos Rivera, Puzzle 163. P+SOD(P)

Crossrefs

Cf. A047791, A048519, A062028 (n + digit sum of n).

Cf. A048523 .. A048527.

Subsequence of A320879 which is subsequence of A320878.

a(1) = A090009(9) = start of first chain of 9 primes under iteration of A062028.

Programs

PARI

is_A320880(n)=isprime(n=A062028(n))&& is_A320879(n)

Formula

A320880 = { n in A320879 | A062028(n) in A320879 }.

Extensions

a(10)-a(15) from Lars Blomberg, Feb 10 2019