A077795 - OEIS

A077795

Numbers k such that (10^k - 1)/9 + 8*10^floor(k/2) is a palindromic wing prime (a.k.a. near-repdigit palindromic prime).

3, 9, 53, 375, 453, 1749, 26619, 68033, 85179

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OFFSET

1,1

COMMENTS

Prime versus probable prime status and proofs are given in the author's table.

a(10) > 400000. - Robert Price, Jan 30 2025

REFERENCES

C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.

LINKS

Patrick De Geest, World!Of Numbers, Palindromic Wing Primes (PWP's)

FORMULA

a(n) = 2*A107649(n) + 1.

EXAMPLE

9 is a term because (10^9 - 1)/9 + 8*10^4 = 111191111.

CROSSREFS

KEYWORD

more,nonn,base

AUTHOR

EXTENSIONS

Name corrected by Jon E. Schoenfield, Oct 30 2018

a(8)-a(9) from Robert Price, Jan 30 2025

STATUS

approved