

A093994


Composite numbers all of whose divisors except the divisor 1 have a prime digital sum.


1



14, 21, 25, 49, 58, 94, 98, 115, 122, 166, 201, 203, 205, 274, 278, 287, 302, 319, 335, 346, 382, 386, 427, 445, 454, 458, 469, 517, 526, 562, 566, 575, 623, 634, 667, 674, 685, 706, 737, 746, 755, 791, 818, 841, 854, 865, 913, 917, 922, 926, 955, 959, 973
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OFFSET

1,1


COMMENTS

Noteworthy members of this sequence are: 854, 38525 and 166286 because they have 7, 11 and 15 divisors with a prime digital sum.


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000


EXAMPLE

a(2)=21 because its divisors are [1, 3, 7, 21] all (except 1) of which have prime digital sums.


MATHEMATICA

digQ[n_] := PrimeQ @ Total @ IntegerDigits[n]; aQ[n_] := CompositeQ[n] && AllTrue[Rest @ Divisors[n], digQ]; Select[Range[1000], aQ] (* Amiram Eldar, Nov 13 2019 *)


CROSSREFS

Sequence in context: A108606 A129497 A255742 * A114985 A001944 A024803
Adjacent sequences: A093991 A093992 A093993 * A093995 A093996 A093997


KEYWORD

base,easy,nonn


AUTHOR

Jason Earls, May 24 2004


STATUS

approved



