A051955 - OEIS

A051955

a(n) = smallest palindrome > a(n-1) such that a(1)*a(2)*...*a(n) + 1 and a(1)*a(2)*...*a(n) - 1 are primes.

4, 363, 434, 484, 494, 636, 4004, 46864, 47474, 135531, 695596, 1793971, 1826281, 1933391, 4700074, 4785874, 4806084, 6462646, 6574756, 9558559, 15399351, 46288264, 53500535, 57499475, 150787051, 185808581, 197636791, 226686622

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..28.

MATHEMATICA

a[1] = 4; a[n_] := a[n] = For[k = a[n-1]+1, True, k++, id = IntegerDigits[k]; If[id == Reverse[id], p = Product[a[j], {j, 1, n - 1}]*k + 1; If[PrimeQ[p] && PrimeQ[p-2], Return[k]]]]; Table[Print["a(", n, ") = ", a[n]]; a[n], {n, 1, 28}] (* Jean-François Alcover, Jul 30 2017 *)

CROSSREFS

Cf. A051896, A051954.

Subsequence of A002113.

Sequence in context: A203034 A215827 A366469 * A177114 A109760 A051181

Adjacent sequences: A051952 A051953 A051954 * A051956 A051957 A051958

KEYWORD

nice,nonn,base

AUTHOR

Felice Russo, Dec 21 1999

EXTENSIONS

a(12)-a(28) from Donovan Johnson, Feb 17 2010

STATUS

approved