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A091939
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Prime numbers with prime sum of any two digits.
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4
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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; internal format)
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OFFSET
| 1,1
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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.
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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.
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CROSSREFS
| Cf. A004022 (repunit primes).
Sequence in context: A088136 A164932 A086244 * A166559 A072185 A105898
Adjacent sequences: A091936 A091937 A091938 * A091940 A091941 A091942
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KEYWORD
| base,nonn
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AUTHOR
| Rick L. Shepherd (rshepherd2(AT)hotmail.com), Feb 16 2004
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