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A091939 Prime numbers with prime sum of any two digits. 4
11, 23, 29, 41, 43, 47, 61, 67, 83, 89, 211, 2111, 4111, 11161, 11411, 16111, 111121, 111211, 111611, 112111, 611111, 1111211, 1114111, 11111141, 11111161, 11141111, 61111111, 1111111121, 1111111411, 1111211111, 1111411111, 1121111111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All repunit primes (A004022) are terms. All other terms contain exactly one nonzero even digit. All non-repunit terms with k>2 digits must contain exactly k-1 copies of the digit 1, including final digit 1 and the remaining digit must be either 2, 4, or 6.

LINKS

Table of n, a(n) for n=1..32.

EXAMPLE

2111 is a term because it is prime and all sums of any two of its digits are

2+1=3 or 1+1=2 both of which are primes.

CROSSREFS

Cf. A004022 (repunit primes).

Sequence in context: A088136 A164932 A086244 * A072185 A105898 A247228

Adjacent sequences:  A091936 A091937 A091938 * A091940 A091941 A091942

KEYWORD

base,nonn

AUTHOR

Rick L. Shepherd, Feb 16 2004

STATUS

approved

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Last modified June 22 15:24 EDT 2021. Contains 345386 sequences. (Running on oeis4.)