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 A178357 Numbers n such that d(1)^1 + d(2)^2 +...+ d(p)^p and d(1)^p + d(2)^p-1 +...+ d(p)^1 are prime numbers, where d(i), i=1..p, are the digits of n. 2
 2, 3, 5, 7, 11, 12, 14, 16, 21, 23, 29, 32, 34, 38, 41, 43, 47, 56, 61, 65, 74, 83, 89, 92, 98, 101, 110, 111, 113, 115, 120, 122, 131, 133, 137, 139, 140, 146, 153, 155, 160, 164, 182, 186, 188, 191, 203, 205, 212, 214, 221, 225, 227, 230, 232, 236, 272, 281, 287, 290, 302, 304, 311, 313, 319, 320, 326, 331 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..68. EXAMPLE 1583 is in the sequence because : 1 + 5^2 + 8^3 + 3^4 = 619 and 1^4 + 5^3 + 8^2 + 3^1 = 193 are prime numbers. MAPLE with(numtheory):for n from 1 to 1000 do:l:=length(n):n0:=n:s1:=0:s2:=0:for m from 1 to l do:q:=n0:u:=irem(q, 10):v:=iquo(q, 10):n0:=v :s1:=s1+u^(l-m+1):s2:=s2+u^m:od: if type(s1, prime)=true and type(s2, prime)=true then printf(`%d, `, n):else fi:od: MATHEMATICA okQ[n_] := Module[{d=IntegerDigits[n], r}, r=Length[d]; PrimeQ[Total[d^Range[r]]] && PrimeQ[Total[d^Range[r, 1, -1]]]]; Select[Range[1000], okQ] CROSSREFS Cf. A139749 A139750 Sequence in context: A139750 A330125 A139749 * A205667 A241506 A361851 Adjacent sequences: A178354 A178355 A178356 * A178358 A178359 A178360 KEYWORD nonn,base AUTHOR Michel Lagneau, Dec 21 2010 STATUS approved

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Last modified May 30 01:11 EDT 2023. Contains 363044 sequences. (Running on oeis4.)