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

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OFFSET

1,1

COMMENTS

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

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

STATUS

approved